Nephrology

Older men with chronic kidney disease (CKD) show higher resting muscle sympathetic nerve activity, but not vascular stiffness, compared with older women, offering clues to the underlying reasons why men with CKD have a higher cardiovascular risk than do women with the disease.

“Although it is well established that sympathetic nerve system activity is chronically elevated in patients with impaired kidney function, we show for the first time that males with CKD have higher resting muscle sympathetic nerve activity compared with females with CKD,” report the authors on research published in the American Journal of Physiology-Renal Physiology.

“For clinicians, the key takeaway is the importance of recognizing sex-specific differences in sympathetic activity and vascular function when assessing cardiovascular risk in CKD patients,” first author Matias G. Zanuzzi, MD, of the Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, told this news organization.

In the general population, cardiovascular risk is lower in younger women vs men, but their risks converge in older age as women develop similar levels of sympathetic overactivity, vascular stiffness, and cardiovascular risk.

However, an exception to that pattern is seen in the CKD population, where men continue to have a higher cardiovascular mortality risk vs women even in older age.

Studies evaluating the reasons for that have been conflicting, with some reporting a tendency of higher muscle sympathetic nerve activity in older women compared with men and others suggest the opposite finding — lower activity vs men.

To further investigate, Dr. Zanuzzi and colleagues enrolled 129 participants, including 96 men and 33 women with stage III or IV CKD.

The mean age of the study participants was 64 years for men and65 years for women. Most had obesity, and importantly, more than 80% of participants in each group was Black. There were no significant differences between the groups in terms of body mass index or comorbidities, including smoking, diabetes, or hypertension.

At two separate study visits, vascular stiffness was assessed with carotid-femoral pulse wave velocity measurement, and resting muscle sympathetic nerve activity was measured using microneurography. 

The results showed that men with CKD had significantly higher resting muscle sympathetic nerve activity compared with women with CKD (68 vs 55 bursts per 100 heartbeats; P = .005), whereas no differences in vascular stiffness were observed between the genders (P = .248).

“The findings suggest that the higher cardiovascular disease risk observed in older males with CKD may be influenced by elevated sympathetic activity,” Dr. Zanuzzi explained.

“However, the lack of significant differences in vascular stiffness between genders implies that additional factors beyond vascular remodeling may contribute to the observed sex-specific differences in cardiovascular risk,” he said.

Of note, resting vascular stiffness was not associated with muscular sympathetic nerve activity in either men or women, which was surprising to the authors, Dr. Zanuzzi noted.

“This underscores the multifactorial nature of vascular pathophysiology in CKD and underscores the need for further research to unravel the underlying mechanisms.”

In other findings, although prior studies have shown a positive correlation between age and resting muscle sympathetic nerve activity in White, healthy women and men without obesity,, no similar relationship was observed in men or women with CKD.

“These findings suggest that the protective effect of younger age on sympathetic function may not be present in the setting of decreased kidney function in both males and females,” the authors note.

In addition, whereas previous research has shown a clear association between sympathetic overactivity and a wide variety of measures of obesity, in the current study, that association was only observed in men with CKD.

Important limitations of the study include the cross-sectional design and that the population was predominantly Black, Dr. Zanuzzi noted.

“Generalizability to other demographic groups may be limited, and future longitudinal studies are needed to validate these findings and explore potential causal relationships,” he said.

The findings underscore “the need for novel therapeutic approaches targeting sympathetic overactivity and vascular stiffness in CKD patients, especially considering the observed sex-specific differences,” Dr. Zanuzzi added. 

“Potential interventions may include pharmacological agents that modulate sympathetic tone or vascular remodeling pathways,” he said.

“Lifestyle modifications focusing on stress reduction and cardiovascular health promotion could also play a crucial role in mitigating cardiovascular risk.”

Dr. Zanuzzi concluded that “tailoring treatment strategies to address these differences may lead to more personalized and effective management approaches, ultimately improving clinical outcomes in this high-risk population.”

The authors had no disclosures to report.

A version of this article first appeared on Medscape.com.

Older men with chronic kidney disease (CKD) show higher resting muscle sympathetic nerve activity, but not vascular stiffness, compared with older women, offering clues to the underlying reasons why men with CKD have a higher cardiovascular risk than do women with the disease.

“Although it is well established that sympathetic nerve system activity is chronically elevated in patients with impaired kidney function, we show for the first time that males with CKD have higher resting muscle sympathetic nerve activity compared with females with CKD,” report the authors on research published in the American Journal of Physiology-Renal Physiology.

“For clinicians, the key takeaway is the importance of recognizing sex-specific differences in sympathetic activity and vascular function when assessing cardiovascular risk in CKD patients,” first author Matias G. Zanuzzi, MD, of the Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, told this news organization.

In the general population, cardiovascular risk is lower in younger women vs men, but their risks converge in older age as women develop similar levels of sympathetic overactivity, vascular stiffness, and cardiovascular risk.

However, an exception to that pattern is seen in the CKD population, where men continue to have a higher cardiovascular mortality risk vs women even in older age.

Studies evaluating the reasons for that have been conflicting, with some reporting a tendency of higher muscle sympathetic nerve activity in older women compared with men and others suggest the opposite finding — lower activity vs men.

To further investigate, Dr. Zanuzzi and colleagues enrolled 129 participants, including 96 men and 33 women with stage III or IV CKD.

The mean age of the study participants was 64 years for men and65 years for women. Most had obesity, and importantly, more than 80% of participants in each group was Black. There were no significant differences between the groups in terms of body mass index or comorbidities, including smoking, diabetes, or hypertension.

At two separate study visits, vascular stiffness was assessed with carotid-femoral pulse wave velocity measurement, and resting muscle sympathetic nerve activity was measured using microneurography. 

The results showed that men with CKD had significantly higher resting muscle sympathetic nerve activity compared with women with CKD (68 vs 55 bursts per 100 heartbeats; P = .005), whereas no differences in vascular stiffness were observed between the genders (P = .248).

“The findings suggest that the higher cardiovascular disease risk observed in older males with CKD may be influenced by elevated sympathetic activity,” Dr. Zanuzzi explained.

“However, the lack of significant differences in vascular stiffness between genders implies that additional factors beyond vascular remodeling may contribute to the observed sex-specific differences in cardiovascular risk,” he said.

Of note, resting vascular stiffness was not associated with muscular sympathetic nerve activity in either men or women, which was surprising to the authors, Dr. Zanuzzi noted.

“This underscores the multifactorial nature of vascular pathophysiology in CKD and underscores the need for further research to unravel the underlying mechanisms.”

In other findings, although prior studies have shown a positive correlation between age and resting muscle sympathetic nerve activity in White, healthy women and men without obesity,, no similar relationship was observed in men or women with CKD.

“These findings suggest that the protective effect of younger age on sympathetic function may not be present in the setting of decreased kidney function in both males and females,” the authors note.

In addition, whereas previous research has shown a clear association between sympathetic overactivity and a wide variety of measures of obesity, in the current study, that association was only observed in men with CKD.

Important limitations of the study include the cross-sectional design and that the population was predominantly Black, Dr. Zanuzzi noted.

“Generalizability to other demographic groups may be limited, and future longitudinal studies are needed to validate these findings and explore potential causal relationships,” he said.

The findings underscore “the need for novel therapeutic approaches targeting sympathetic overactivity and vascular stiffness in CKD patients, especially considering the observed sex-specific differences,” Dr. Zanuzzi added. 

“Potential interventions may include pharmacological agents that modulate sympathetic tone or vascular remodeling pathways,” he said.

“Lifestyle modifications focusing on stress reduction and cardiovascular health promotion could also play a crucial role in mitigating cardiovascular risk.”

Dr. Zanuzzi concluded that “tailoring treatment strategies to address these differences may lead to more personalized and effective management approaches, ultimately improving clinical outcomes in this high-risk population.”

The authors had no disclosures to report.

A version of this article first appeared on Medscape.com.

Older men with chronic kidney disease (CKD) show higher resting muscle sympathetic nerve activity, but not vascular stiffness, compared with older women, offering clues to the underlying reasons why men with CKD have a higher cardiovascular risk than do women with the disease.

“Although it is well established that sympathetic nerve system activity is chronically elevated in patients with impaired kidney function, we show for the first time that males with CKD have higher resting muscle sympathetic nerve activity compared with females with CKD,” report the authors on research published in the American Journal of Physiology-Renal Physiology.

“For clinicians, the key takeaway is the importance of recognizing sex-specific differences in sympathetic activity and vascular function when assessing cardiovascular risk in CKD patients,” first author Matias G. Zanuzzi, MD, of the Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, told this news organization.

In the general population, cardiovascular risk is lower in younger women vs men, but their risks converge in older age as women develop similar levels of sympathetic overactivity, vascular stiffness, and cardiovascular risk.

However, an exception to that pattern is seen in the CKD population, where men continue to have a higher cardiovascular mortality risk vs women even in older age.

Studies evaluating the reasons for that have been conflicting, with some reporting a tendency of higher muscle sympathetic nerve activity in older women compared with men and others suggest the opposite finding — lower activity vs men.

To further investigate, Dr. Zanuzzi and colleagues enrolled 129 participants, including 96 men and 33 women with stage III or IV CKD.

The mean age of the study participants was 64 years for men and65 years for women. Most had obesity, and importantly, more than 80% of participants in each group was Black. There were no significant differences between the groups in terms of body mass index or comorbidities, including smoking, diabetes, or hypertension.

At two separate study visits, vascular stiffness was assessed with carotid-femoral pulse wave velocity measurement, and resting muscle sympathetic nerve activity was measured using microneurography. 

The results showed that men with CKD had significantly higher resting muscle sympathetic nerve activity compared with women with CKD (68 vs 55 bursts per 100 heartbeats; P = .005), whereas no differences in vascular stiffness were observed between the genders (P = .248).

“The findings suggest that the higher cardiovascular disease risk observed in older males with CKD may be influenced by elevated sympathetic activity,” Dr. Zanuzzi explained.

“However, the lack of significant differences in vascular stiffness between genders implies that additional factors beyond vascular remodeling may contribute to the observed sex-specific differences in cardiovascular risk,” he said.

Of note, resting vascular stiffness was not associated with muscular sympathetic nerve activity in either men or women, which was surprising to the authors, Dr. Zanuzzi noted.

“This underscores the multifactorial nature of vascular pathophysiology in CKD and underscores the need for further research to unravel the underlying mechanisms.”

In other findings, although prior studies have shown a positive correlation between age and resting muscle sympathetic nerve activity in White, healthy women and men without obesity,, no similar relationship was observed in men or women with CKD.

“These findings suggest that the protective effect of younger age on sympathetic function may not be present in the setting of decreased kidney function in both males and females,” the authors note.

In addition, whereas previous research has shown a clear association between sympathetic overactivity and a wide variety of measures of obesity, in the current study, that association was only observed in men with CKD.

Important limitations of the study include the cross-sectional design and that the population was predominantly Black, Dr. Zanuzzi noted.

“Generalizability to other demographic groups may be limited, and future longitudinal studies are needed to validate these findings and explore potential causal relationships,” he said.

The findings underscore “the need for novel therapeutic approaches targeting sympathetic overactivity and vascular stiffness in CKD patients, especially considering the observed sex-specific differences,” Dr. Zanuzzi added. 

“Potential interventions may include pharmacological agents that modulate sympathetic tone or vascular remodeling pathways,” he said.

“Lifestyle modifications focusing on stress reduction and cardiovascular health promotion could also play a crucial role in mitigating cardiovascular risk.”

Dr. Zanuzzi concluded that “tailoring treatment strategies to address these differences may lead to more personalized and effective management approaches, ultimately improving clinical outcomes in this high-risk population.”

The authors had no disclosures to report.

A version of this article first appeared on Medscape.com.

Some of the best clinical trials of patients with antineutrophil cytoplasmic antibody–associated vasculitis (AAV) that were presented at the 21st International Vasculitis Workshop in Barcelona, Spain, included studies addressing relapse after stopping steroids, preventing relapse with abatacept, improving kidney function with plasma exchange, and vaccinating rituximab-treated patients.
 

Stopping Steroids After Remission in GPA

In the randomized, open-label TAPIR (The Assessment of Prednisone In Remission Trial) study of 159 adults with GPA in remission who had tapered to a prednisone dose of 5 mg/day, those who remained at that dosage had a significantly lower rate of relapse after 6 months than those who tapered to 0 mg/day (4.2% vs 15.5%; P = .227), according to results reported at the meeting.

However, use of a higher dose of prednisone for disease relapse by 6 months was similar for patients who used rituximab at baseline (8.8% with 0 mg/day vs 6.1% with 5 mg/day; P = .667), and the difference in this primary outcome was more pronounced among patients who did not take rituximab at baseline (20.0% with 0 mg/day vs 2.6% with 5 mg/day; P = .023).

A higher percentage of patients taking prednisone 0 mg/day had disease relapses that were considered minor (14.1% and 4.2%; P = .0391). Major relapses occurred in none of the patients taking 5 mg/day and in 1.4% receiving 0 mg/day. About 90% of patients in either treatment arm completed the trial.

The study, funded by the National Institute of Arthritis and Musculoskelatal and Skin Diseases and the National Heart Lung and Blood Institute, was unique in that half of patients randomized in the study were enrolled at community clinics and half were enrolled at Vasculitis Clinical Research Consortium clinical centers.
 

Abatacept Falls Short for Preventing Relapse in GPA

Adding abatacept to glucocorticoids failed to reduce risk of relapse, worsening disease, or failure to reach remission in adults with relapsing, nonsevere GPA, based on data from a randomized trial of 65 individuals.

In the 20-site, randomized, double-blind ABROGATE (Abatacept for the Treatment of Relapsing, Non-Severe, Granulomatosis With Polyangiitis) study, 34 patients received 125 mg subcutaneous abatacept once a week or a placebo in addition to 30 mg/day of prednisone that was tapered and discontinued after 12 weeks. Patients who were receiving methotrexate, azathioprine, mycophenolate, or leflunomide at baseline continued the medication at a stable dose.

The primary outcome of disease worsening or relapse occurred in 62% of the abatacept group and 68% of the placebo group, and no significant difference in treatment failure rate appeared between the groups. In addition, key secondary endpoints of time to full remission, duration of glucocorticoid-free remission, relapse severity, prevention of damage, and patient-reported quality of life outcomes were not significantly different between the groups.

A total of 112 adverse events occurred, with similar type and severity between the groups, including incidence of infections.

The findings were limited by the relatively small sample size, but the results suggest a need for further research to determine mechanisms of disease and explore additional novel treatments for this rare patient population, the researchers wrote in their abstract.

The study was funded by the National Institutes of Health and Bristol-Myers Squibb.
 

Plasma Exchange Improves Kidney Function in AAV

Use of therapeutic plasma exchange (PLEX) as an adjunct treatment improved early kidney function in adults with AAV and glomerulonephritis but did not extend beyond 8 weeks, and recovery of kidney function was no different between patients receiving a regular glucocorticoid regimen versus a reduced course, based on a post-hoc analysis of 691 individuals in the international randomized controlled trial called PEXIVAS.

The primary outcomes of change in kidney function based on estimated glomerular filtration rate (eGFR) from baseline over 1 year and the percentage of patients with improvement in eGFR of at least 15 mL/min/1.73 m² at weeks 12, 26, and 52.

The rate of improved eGFR was significantly greater in the PLEX group, compared with controls, at 2, 4, and 8 weeks. At 4 weeks, significantly more patients in the PLEX group had an increase in eGFR by at least 15 mL/min/1.73 m², compared with the control group (relative risk [RR], 1.41; P = .008). In addition, improved kidney function within 4 weeks was significantly associated with lower risk of kidney failure within 1 year, regardless of treatment group.

The original PEXIVAS trial was supported by various government institutes and agencies from multiple countries.
 

Reinforced Vaccine Strategy with Rituximab Improved Antibody Response in AAV

A vaccine strategy consisting of a double dose of 13-valent antipneumococcal conjugate vaccine (PCV13) at day 0 and day 7 followed by a single dose of 23-valent unconjugated pneumococcal polysaccharide vaccine (PPV23) at 5 months significantly improved antibody responses against Streptococcus pneumoniae in patients with AAV, compared with standard treatment, based on data from 95 individuals in the multicenter, open-label study called PNEUMOVAS.

Adults with newly diagnosed AAV were randomly assigned to one of three treatment arms: a standard regimen of one dose of PCV13 at day 0 and one dose of PPV23 at month 5 (arm 1); a double dose of PCV13 at day 0 and day 7 with a dose of PPV23 at month 5 (arm 2); or four doses of PCV13 at day 0 and one dose of PPV23 at month 5 (arm 3). These patients received PCV13 within 2 days before or after their first infusion of rituximab.

The primary endpoint was positive antibody response against 12 pneumococcal subtypes common to the PCV13 and PCV23 vaccines at 6 months. At 6 months, the immune response to 0-3, 4-6, 7-9, or 10-12 serotypes was 83.3%, 13.3%, 3.3%, and 0%, respectively, in arm 1; 56.3%, 28.1%, 15.6%, and 0% in arm 2; and 60.6%, 33.3%, 6.1%, and 0% in arm 3.

No severe adverse events related to vaccination were observed in any of the groups; a total of eight AAV flares occurred in six patients (one in arm 1, two in arm 2, and three in arm 3). Local and systemic reactions occurred more frequently with the reinforced dose regimens, but these were mostly grade 1 or 2 local reactions.

The study was supported by the French Ministry of Health.

Some of the best clinical trials of patients with antineutrophil cytoplasmic antibody–associated vasculitis (AAV) that were presented at the 21st International Vasculitis Workshop in Barcelona, Spain, included studies addressing relapse after stopping steroids, preventing relapse with abatacept, improving kidney function with plasma exchange, and vaccinating rituximab-treated patients.
 

Stopping Steroids After Remission in GPA

In the randomized, open-label TAPIR (The Assessment of Prednisone In Remission Trial) study of 159 adults with GPA in remission who had tapered to a prednisone dose of 5 mg/day, those who remained at that dosage had a significantly lower rate of relapse after 6 months than those who tapered to 0 mg/day (4.2% vs 15.5%; P = .227), according to results reported at the meeting.

However, use of a higher dose of prednisone for disease relapse by 6 months was similar for patients who used rituximab at baseline (8.8% with 0 mg/day vs 6.1% with 5 mg/day; P = .667), and the difference in this primary outcome was more pronounced among patients who did not take rituximab at baseline (20.0% with 0 mg/day vs 2.6% with 5 mg/day; P = .023).

A higher percentage of patients taking prednisone 0 mg/day had disease relapses that were considered minor (14.1% and 4.2%; P = .0391). Major relapses occurred in none of the patients taking 5 mg/day and in 1.4% receiving 0 mg/day. About 90% of patients in either treatment arm completed the trial.

The study, funded by the National Institute of Arthritis and Musculoskelatal and Skin Diseases and the National Heart Lung and Blood Institute, was unique in that half of patients randomized in the study were enrolled at community clinics and half were enrolled at Vasculitis Clinical Research Consortium clinical centers.
 

Abatacept Falls Short for Preventing Relapse in GPA

Adding abatacept to glucocorticoids failed to reduce risk of relapse, worsening disease, or failure to reach remission in adults with relapsing, nonsevere GPA, based on data from a randomized trial of 65 individuals.

In the 20-site, randomized, double-blind ABROGATE (Abatacept for the Treatment of Relapsing, Non-Severe, Granulomatosis With Polyangiitis) study, 34 patients received 125 mg subcutaneous abatacept once a week or a placebo in addition to 30 mg/day of prednisone that was tapered and discontinued after 12 weeks. Patients who were receiving methotrexate, azathioprine, mycophenolate, or leflunomide at baseline continued the medication at a stable dose.

The primary outcome of disease worsening or relapse occurred in 62% of the abatacept group and 68% of the placebo group, and no significant difference in treatment failure rate appeared between the groups. In addition, key secondary endpoints of time to full remission, duration of glucocorticoid-free remission, relapse severity, prevention of damage, and patient-reported quality of life outcomes were not significantly different between the groups.

A total of 112 adverse events occurred, with similar type and severity between the groups, including incidence of infections.

The findings were limited by the relatively small sample size, but the results suggest a need for further research to determine mechanisms of disease and explore additional novel treatments for this rare patient population, the researchers wrote in their abstract.

The study was funded by the National Institutes of Health and Bristol-Myers Squibb.
 

Plasma Exchange Improves Kidney Function in AAV

Use of therapeutic plasma exchange (PLEX) as an adjunct treatment improved early kidney function in adults with AAV and glomerulonephritis but did not extend beyond 8 weeks, and recovery of kidney function was no different between patients receiving a regular glucocorticoid regimen versus a reduced course, based on a post-hoc analysis of 691 individuals in the international randomized controlled trial called PEXIVAS.

The primary outcomes of change in kidney function based on estimated glomerular filtration rate (eGFR) from baseline over 1 year and the percentage of patients with improvement in eGFR of at least 15 mL/min/1.73 m² at weeks 12, 26, and 52.

The rate of improved eGFR was significantly greater in the PLEX group, compared with controls, at 2, 4, and 8 weeks. At 4 weeks, significantly more patients in the PLEX group had an increase in eGFR by at least 15 mL/min/1.73 m², compared with the control group (relative risk [RR], 1.41; P = .008). In addition, improved kidney function within 4 weeks was significantly associated with lower risk of kidney failure within 1 year, regardless of treatment group.

The original PEXIVAS trial was supported by various government institutes and agencies from multiple countries.
 

Reinforced Vaccine Strategy with Rituximab Improved Antibody Response in AAV

A vaccine strategy consisting of a double dose of 13-valent antipneumococcal conjugate vaccine (PCV13) at day 0 and day 7 followed by a single dose of 23-valent unconjugated pneumococcal polysaccharide vaccine (PPV23) at 5 months significantly improved antibody responses against Streptococcus pneumoniae in patients with AAV, compared with standard treatment, based on data from 95 individuals in the multicenter, open-label study called PNEUMOVAS.

Adults with newly diagnosed AAV were randomly assigned to one of three treatment arms: a standard regimen of one dose of PCV13 at day 0 and one dose of PPV23 at month 5 (arm 1); a double dose of PCV13 at day 0 and day 7 with a dose of PPV23 at month 5 (arm 2); or four doses of PCV13 at day 0 and one dose of PPV23 at month 5 (arm 3). These patients received PCV13 within 2 days before or after their first infusion of rituximab.

The primary endpoint was positive antibody response against 12 pneumococcal subtypes common to the PCV13 and PCV23 vaccines at 6 months. At 6 months, the immune response to 0-3, 4-6, 7-9, or 10-12 serotypes was 83.3%, 13.3%, 3.3%, and 0%, respectively, in arm 1; 56.3%, 28.1%, 15.6%, and 0% in arm 2; and 60.6%, 33.3%, 6.1%, and 0% in arm 3.

No severe adverse events related to vaccination were observed in any of the groups; a total of eight AAV flares occurred in six patients (one in arm 1, two in arm 2, and three in arm 3). Local and systemic reactions occurred more frequently with the reinforced dose regimens, but these were mostly grade 1 or 2 local reactions.

The study was supported by the French Ministry of Health.

Some of the best clinical trials of patients with antineutrophil cytoplasmic antibody–associated vasculitis (AAV) that were presented at the 21st International Vasculitis Workshop in Barcelona, Spain, included studies addressing relapse after stopping steroids, preventing relapse with abatacept, improving kidney function with plasma exchange, and vaccinating rituximab-treated patients.
 

Stopping Steroids After Remission in GPA

In the randomized, open-label TAPIR (The Assessment of Prednisone In Remission Trial) study of 159 adults with GPA in remission who had tapered to a prednisone dose of 5 mg/day, those who remained at that dosage had a significantly lower rate of relapse after 6 months than those who tapered to 0 mg/day (4.2% vs 15.5%; P = .227), according to results reported at the meeting.

However, use of a higher dose of prednisone for disease relapse by 6 months was similar for patients who used rituximab at baseline (8.8% with 0 mg/day vs 6.1% with 5 mg/day; P = .667), and the difference in this primary outcome was more pronounced among patients who did not take rituximab at baseline (20.0% with 0 mg/day vs 2.6% with 5 mg/day; P = .023).

A higher percentage of patients taking prednisone 0 mg/day had disease relapses that were considered minor (14.1% and 4.2%; P = .0391). Major relapses occurred in none of the patients taking 5 mg/day and in 1.4% receiving 0 mg/day. About 90% of patients in either treatment arm completed the trial.

The study, funded by the National Institute of Arthritis and Musculoskelatal and Skin Diseases and the National Heart Lung and Blood Institute, was unique in that half of patients randomized in the study were enrolled at community clinics and half were enrolled at Vasculitis Clinical Research Consortium clinical centers.
 

Abatacept Falls Short for Preventing Relapse in GPA

Adding abatacept to glucocorticoids failed to reduce risk of relapse, worsening disease, or failure to reach remission in adults with relapsing, nonsevere GPA, based on data from a randomized trial of 65 individuals.

In the 20-site, randomized, double-blind ABROGATE (Abatacept for the Treatment of Relapsing, Non-Severe, Granulomatosis With Polyangiitis) study, 34 patients received 125 mg subcutaneous abatacept once a week or a placebo in addition to 30 mg/day of prednisone that was tapered and discontinued after 12 weeks. Patients who were receiving methotrexate, azathioprine, mycophenolate, or leflunomide at baseline continued the medication at a stable dose.

The primary outcome of disease worsening or relapse occurred in 62% of the abatacept group and 68% of the placebo group, and no significant difference in treatment failure rate appeared between the groups. In addition, key secondary endpoints of time to full remission, duration of glucocorticoid-free remission, relapse severity, prevention of damage, and patient-reported quality of life outcomes were not significantly different between the groups.

A total of 112 adverse events occurred, with similar type and severity between the groups, including incidence of infections.

The findings were limited by the relatively small sample size, but the results suggest a need for further research to determine mechanisms of disease and explore additional novel treatments for this rare patient population, the researchers wrote in their abstract.

The study was funded by the National Institutes of Health and Bristol-Myers Squibb.
 

Plasma Exchange Improves Kidney Function in AAV

Use of therapeutic plasma exchange (PLEX) as an adjunct treatment improved early kidney function in adults with AAV and glomerulonephritis but did not extend beyond 8 weeks, and recovery of kidney function was no different between patients receiving a regular glucocorticoid regimen versus a reduced course, based on a post-hoc analysis of 691 individuals in the international randomized controlled trial called PEXIVAS.

The primary outcomes of change in kidney function based on estimated glomerular filtration rate (eGFR) from baseline over 1 year and the percentage of patients with improvement in eGFR of at least 15 mL/min/1.73 m² at weeks 12, 26, and 52.

The rate of improved eGFR was significantly greater in the PLEX group, compared with controls, at 2, 4, and 8 weeks. At 4 weeks, significantly more patients in the PLEX group had an increase in eGFR by at least 15 mL/min/1.73 m², compared with the control group (relative risk [RR], 1.41; P = .008). In addition, improved kidney function within 4 weeks was significantly associated with lower risk of kidney failure within 1 year, regardless of treatment group.

The original PEXIVAS trial was supported by various government institutes and agencies from multiple countries.
 

Reinforced Vaccine Strategy with Rituximab Improved Antibody Response in AAV

A vaccine strategy consisting of a double dose of 13-valent antipneumococcal conjugate vaccine (PCV13) at day 0 and day 7 followed by a single dose of 23-valent unconjugated pneumococcal polysaccharide vaccine (PPV23) at 5 months significantly improved antibody responses against Streptococcus pneumoniae in patients with AAV, compared with standard treatment, based on data from 95 individuals in the multicenter, open-label study called PNEUMOVAS.

Adults with newly diagnosed AAV were randomly assigned to one of three treatment arms: a standard regimen of one dose of PCV13 at day 0 and one dose of PPV23 at month 5 (arm 1); a double dose of PCV13 at day 0 and day 7 with a dose of PPV23 at month 5 (arm 2); or four doses of PCV13 at day 0 and one dose of PPV23 at month 5 (arm 3). These patients received PCV13 within 2 days before or after their first infusion of rituximab.

The primary endpoint was positive antibody response against 12 pneumococcal subtypes common to the PCV13 and PCV23 vaccines at 6 months. At 6 months, the immune response to 0-3, 4-6, 7-9, or 10-12 serotypes was 83.3%, 13.3%, 3.3%, and 0%, respectively, in arm 1; 56.3%, 28.1%, 15.6%, and 0% in arm 2; and 60.6%, 33.3%, 6.1%, and 0% in arm 3.

No severe adverse events related to vaccination were observed in any of the groups; a total of eight AAV flares occurred in six patients (one in arm 1, two in arm 2, and three in arm 3). Local and systemic reactions occurred more frequently with the reinforced dose regimens, but these were mostly grade 1 or 2 local reactions.

The study was supported by the French Ministry of Health.

TOPLINE:

Trimethylamine N-oxide (TMAO) is a gut microbiota-derived metabolite generated by metabolism of dietary L-carnitine, primarily from red meat, and choline, from a variety of animal source foods. TMAO has been shown to cause kidney injury and tubulointerstitial fibrosis in experimental models.

In this study, TMAO was independently associated with higher risks for incident chronic kidney disease (CKD) and faster kidney function decline in humans.

The findings suggest that TMAO may be a novel risk factor and intervention target for CKD prevention and treatment.

METHODOLOGY:

• Study population was 10,564 participants from two community-based, prospective cohorts without baseline CKD (estimated glomerular filtration rate [eGFR] ≥ 60 mL/min/1.73 m²).
• Incident CKD was defined as eGFR decline ≥ 30% from baseline, resulting in eGFR < 60 mL/min/1.73 m².

TAKEAWAY:

• During a median 9.4 years, 979 incident CKD events occurred.
• Correlation between baseline TMAO and total meat intake was small but statistically significant (P = .08).
• After adjustments for sociodemographic, lifestyle, diet, and cardiovascular risk factors, higher plasma TMAO was associated with more than doubled CKD incidence (hazard ratio, 2.24 for top vs bottom quintile).
• Higher TMAO levels were also associated with greater annual eGFR decline (top vs bottom quintile eGFR change = −0.43 mL/min/1.73 m² per year.
• Compared with other major CKD risk factors, the association for the top vs bottom TMAO quintile (−0.43 mL/min/1.73 m² per year) was similar to that seen per 10 years of older age (−0.43) and presence of diabetes (−0.51), and larger than that seen comparing Black vs non-Black race (−0.28) and per 10 mm Hg systolic blood pressure (−0.16).

IN PRACTICE:

“TMAO levels are highly modifiable by both lifestyle-like diet and pharmacologic interventions. Besides using novel drugs to lower TMAO in patients, using dietary interventions to lower TMAO in the general population could be a cost-efficient and low-risk preventive strategy for chronic kidney disease development. ... These findings support future studies to investigate whether lifestyle and pharmacologic interventions to lower TMAO may prevent CKD development and progression.”

SOURCE:

The study was conducted by Meng Wang, PhD, of Tufts University, Boston, and colleagues and published online in the Journal of the American Society of Nephrology.

LIMITATIONS:

Observational design, can’t exclude residual confounding.

Inter-assay variability.

Use of International Classification of Diseases codes for hospitalization-based CKD, subject to reporting errors.

DISCLOSURES:

The study was supported by grants from the National Institutes of Health and an American Heart Association Postdoctoral Fellowship. Dr. Wang had no disclosures but several coauthors have patents on various diagnostics and/or industry disclosures.

A version of this article appeared on Medscape.com.

TOPLINE:

Trimethylamine N-oxide (TMAO) is a gut microbiota-derived metabolite generated by metabolism of dietary L-carnitine, primarily from red meat, and choline, from a variety of animal source foods. TMAO has been shown to cause kidney injury and tubulointerstitial fibrosis in experimental models.

In this study, TMAO was independently associated with higher risks for incident chronic kidney disease (CKD) and faster kidney function decline in humans.

The findings suggest that TMAO may be a novel risk factor and intervention target for CKD prevention and treatment.

METHODOLOGY:

• Study population was 10,564 participants from two community-based, prospective cohorts without baseline CKD (estimated glomerular filtration rate [eGFR] ≥ 60 mL/min/1.73 m²).
• Incident CKD was defined as eGFR decline ≥ 30% from baseline, resulting in eGFR < 60 mL/min/1.73 m².

TAKEAWAY:

• During a median 9.4 years, 979 incident CKD events occurred.
• Correlation between baseline TMAO and total meat intake was small but statistically significant (P = .08).
• After adjustments for sociodemographic, lifestyle, diet, and cardiovascular risk factors, higher plasma TMAO was associated with more than doubled CKD incidence (hazard ratio, 2.24 for top vs bottom quintile).
• Higher TMAO levels were also associated with greater annual eGFR decline (top vs bottom quintile eGFR change = −0.43 mL/min/1.73 m² per year.
• Compared with other major CKD risk factors, the association for the top vs bottom TMAO quintile (−0.43 mL/min/1.73 m² per year) was similar to that seen per 10 years of older age (−0.43) and presence of diabetes (−0.51), and larger than that seen comparing Black vs non-Black race (−0.28) and per 10 mm Hg systolic blood pressure (−0.16).

IN PRACTICE:

“TMAO levels are highly modifiable by both lifestyle-like diet and pharmacologic interventions. Besides using novel drugs to lower TMAO in patients, using dietary interventions to lower TMAO in the general population could be a cost-efficient and low-risk preventive strategy for chronic kidney disease development. ... These findings support future studies to investigate whether lifestyle and pharmacologic interventions to lower TMAO may prevent CKD development and progression.”

SOURCE:

The study was conducted by Meng Wang, PhD, of Tufts University, Boston, and colleagues and published online in the Journal of the American Society of Nephrology.

LIMITATIONS:

Observational design, can’t exclude residual confounding.

Inter-assay variability.

Use of International Classification of Diseases codes for hospitalization-based CKD, subject to reporting errors.

DISCLOSURES:

The study was supported by grants from the National Institutes of Health and an American Heart Association Postdoctoral Fellowship. Dr. Wang had no disclosures but several coauthors have patents on various diagnostics and/or industry disclosures.

A version of this article appeared on Medscape.com.

TOPLINE:

Trimethylamine N-oxide (TMAO) is a gut microbiota-derived metabolite generated by metabolism of dietary L-carnitine, primarily from red meat, and choline, from a variety of animal source foods. TMAO has been shown to cause kidney injury and tubulointerstitial fibrosis in experimental models.

In this study, TMAO was independently associated with higher risks for incident chronic kidney disease (CKD) and faster kidney function decline in humans.

The findings suggest that TMAO may be a novel risk factor and intervention target for CKD prevention and treatment.

METHODOLOGY:

• Study population was 10,564 participants from two community-based, prospective cohorts without baseline CKD (estimated glomerular filtration rate [eGFR] ≥ 60 mL/min/1.73 m²).
• Incident CKD was defined as eGFR decline ≥ 30% from baseline, resulting in eGFR < 60 mL/min/1.73 m².

TAKEAWAY:

• During a median 9.4 years, 979 incident CKD events occurred.
• Correlation between baseline TMAO and total meat intake was small but statistically significant (P = .08).
• After adjustments for sociodemographic, lifestyle, diet, and cardiovascular risk factors, higher plasma TMAO was associated with more than doubled CKD incidence (hazard ratio, 2.24 for top vs bottom quintile).
• Higher TMAO levels were also associated with greater annual eGFR decline (top vs bottom quintile eGFR change = −0.43 mL/min/1.73 m² per year.
• Compared with other major CKD risk factors, the association for the top vs bottom TMAO quintile (−0.43 mL/min/1.73 m² per year) was similar to that seen per 10 years of older age (−0.43) and presence of diabetes (−0.51), and larger than that seen comparing Black vs non-Black race (−0.28) and per 10 mm Hg systolic blood pressure (−0.16).

IN PRACTICE:

“TMAO levels are highly modifiable by both lifestyle-like diet and pharmacologic interventions. Besides using novel drugs to lower TMAO in patients, using dietary interventions to lower TMAO in the general population could be a cost-efficient and low-risk preventive strategy for chronic kidney disease development. ... These findings support future studies to investigate whether lifestyle and pharmacologic interventions to lower TMAO may prevent CKD development and progression.”

SOURCE:

The study was conducted by Meng Wang, PhD, of Tufts University, Boston, and colleagues and published online in the Journal of the American Society of Nephrology.

LIMITATIONS:

Observational design, can’t exclude residual confounding.

Inter-assay variability.

Use of International Classification of Diseases codes for hospitalization-based CKD, subject to reporting errors.

DISCLOSURES:

The study was supported by grants from the National Institutes of Health and an American Heart Association Postdoctoral Fellowship. Dr. Wang had no disclosures but several coauthors have patents on various diagnostics and/or industry disclosures.

A version of this article appeared on Medscape.com.

Immunoglobulin A (IgA) nephropathy, also known as Berger disease, is a kidney disorder characterized by the deposition of IgA in the glomeruli, leading to inflammation and potential damage. It is the most common primary glomerulonephritis worldwide. Here are five things to know about IgA nephropathy.

1. Disease-modifying therapies for IgA nephropathy have become available only recently.

The past few years have brought development of the first disease-modifying therapies to reduce proteinuria for adults with primary IgA nephropathy who are at risk for rapid disease progression. In 2021, the US Food and Drug Administration (FDA) approved a targeted-release formulation of the corticosteroid budesonide for these patients. This formulation delivers the drug to the distal ileum, targeting Peyer patches — the site of IgA production — while minimizing the adverse effects associated with systemic corticosteroid therapy.

The FDA most recently approved sparsentan, a nonimmunosuppressive therapy that combines an endothelin type A receptor antagonist with an angiotensin II type 1 receptor antagonist, for the same indication in 2023.

In addition, several studies have reported benefits with the use of sodium-glucose cotransporter 2 (SGLT2) inhibitors in the treatment of patients with IgA nephropathy at high risk for progression, although this use is still investigational.

2. The most common sign in patients with IgA nephropathy is blood in the urine.

The most common clinical manifestation of IgA nephropathy is microscopic or gross hematuria. Hematuria is often recurrent and may follow upper respiratory tract or other infections. The presence of blood in the urine may be episodic and can vary in severity.

Proteinuria is another key feature of IgA nephropathy. It may range from mild to moderate and, in some cases, can even progress to nephrotic-range proteinuria. The level of proteinuria is an important indicator of disease severity and prognosis. Persistent and significant proteinuria may be associated with an increased risk for progression to chronic kidney disease.

3. Five histologic features are widely used to predict clinical outcomes.

The Oxford classification of IgA nephropathy, or MEST score, published in 2009, comprises four histologic features that are independent predictors of clinical outcome: mesangial and endocapillary hypercellularity, segmental glomerulosclerosis, and interstitial fibrosis/tubular atrophy. In 2017, the IgA Nephropathy Classification Working Group added glomerular crescent formation to the Oxford classification, to form the MEST-C score.

If any of these features are seen, the prognosis can generally be assumed to be poor. Proteinuria, hypertension, elevated creatinine, and a decreased estimated glomerular filtration rate are some of the other factors that can contribute to poor clinical outcomes in patients with IgA nephropathy.

4. IgA nephropathy can eventually progress to end-stage kidney disease.

Progressive kidney dysfunction can occur in some individuals with IgA nephropathy. This may manifest as a gradual decline in glomerular filtration rate, leading to chronic kidney disease over time. In addition, up to 20% of patients progress to end-stage kidney disease within 10 years. The risk for renal impairment varies among individuals, and certain clinical and histologic features may influence the prognosis.

Hypertension is a common complication of IgA nephropathy. The mechanisms underlying hypertension in IgA nephropathy are complex and may involve alterations in the renin-angiotensin-aldosterone system and salt-water balance. Controlling blood pressure is important in managing IgA nephropathy to help slow the progression of kidney damage.

5. Definitive diagnosis requires a renal biopsy.

There are currently no validated diagnostic serum or urine biomarkers for IgA nephropathy, which, according to KDIGO (Kidney Disease: Improving Global Outcomes), requires a renal biopsy to make a definitive diagnosis. The characteristic finding is the deposition of IgA in the glomeruli, typically in the mesangial area. The biopsy can also provide information about the degree of inflammation, scarring, and other histologic features that help guide treatment decisions and predict outcomes.

Dr. Alper, associate professor, department of medicine, section of nephrology, Tulane University School of Medicine, New Orleans, has disclosed no relevant financial relationships.

A version of this article appeared on Medscape.com.

Immunoglobulin A (IgA) nephropathy, also known as Berger disease, is a kidney disorder characterized by the deposition of IgA in the glomeruli, leading to inflammation and potential damage. It is the most common primary glomerulonephritis worldwide. Here are five things to know about IgA nephropathy.

1. Disease-modifying therapies for IgA nephropathy have become available only recently.

The past few years have brought development of the first disease-modifying therapies to reduce proteinuria for adults with primary IgA nephropathy who are at risk for rapid disease progression. In 2021, the US Food and Drug Administration (FDA) approved a targeted-release formulation of the corticosteroid budesonide for these patients. This formulation delivers the drug to the distal ileum, targeting Peyer patches — the site of IgA production — while minimizing the adverse effects associated with systemic corticosteroid therapy.

The FDA most recently approved sparsentan, a nonimmunosuppressive therapy that combines an endothelin type A receptor antagonist with an angiotensin II type 1 receptor antagonist, for the same indication in 2023.

In addition, several studies have reported benefits with the use of sodium-glucose cotransporter 2 (SGLT2) inhibitors in the treatment of patients with IgA nephropathy at high risk for progression, although this use is still investigational.

2. The most common sign in patients with IgA nephropathy is blood in the urine.

The most common clinical manifestation of IgA nephropathy is microscopic or gross hematuria. Hematuria is often recurrent and may follow upper respiratory tract or other infections. The presence of blood in the urine may be episodic and can vary in severity.

Proteinuria is another key feature of IgA nephropathy. It may range from mild to moderate and, in some cases, can even progress to nephrotic-range proteinuria. The level of proteinuria is an important indicator of disease severity and prognosis. Persistent and significant proteinuria may be associated with an increased risk for progression to chronic kidney disease.

3. Five histologic features are widely used to predict clinical outcomes.

The Oxford classification of IgA nephropathy, or MEST score, published in 2009, comprises four histologic features that are independent predictors of clinical outcome: mesangial and endocapillary hypercellularity, segmental glomerulosclerosis, and interstitial fibrosis/tubular atrophy. In 2017, the IgA Nephropathy Classification Working Group added glomerular crescent formation to the Oxford classification, to form the MEST-C score.

If any of these features are seen, the prognosis can generally be assumed to be poor. Proteinuria, hypertension, elevated creatinine, and a decreased estimated glomerular filtration rate are some of the other factors that can contribute to poor clinical outcomes in patients with IgA nephropathy.

4. IgA nephropathy can eventually progress to end-stage kidney disease.

Progressive kidney dysfunction can occur in some individuals with IgA nephropathy. This may manifest as a gradual decline in glomerular filtration rate, leading to chronic kidney disease over time. In addition, up to 20% of patients progress to end-stage kidney disease within 10 years. The risk for renal impairment varies among individuals, and certain clinical and histologic features may influence the prognosis.

Hypertension is a common complication of IgA nephropathy. The mechanisms underlying hypertension in IgA nephropathy are complex and may involve alterations in the renin-angiotensin-aldosterone system and salt-water balance. Controlling blood pressure is important in managing IgA nephropathy to help slow the progression of kidney damage.

5. Definitive diagnosis requires a renal biopsy.

There are currently no validated diagnostic serum or urine biomarkers for IgA nephropathy, which, according to KDIGO (Kidney Disease: Improving Global Outcomes), requires a renal biopsy to make a definitive diagnosis. The characteristic finding is the deposition of IgA in the glomeruli, typically in the mesangial area. The biopsy can also provide information about the degree of inflammation, scarring, and other histologic features that help guide treatment decisions and predict outcomes.

Dr. Alper, associate professor, department of medicine, section of nephrology, Tulane University School of Medicine, New Orleans, has disclosed no relevant financial relationships.

A version of this article appeared on Medscape.com.

Immunoglobulin A (IgA) nephropathy, also known as Berger disease, is a kidney disorder characterized by the deposition of IgA in the glomeruli, leading to inflammation and potential damage. It is the most common primary glomerulonephritis worldwide. Here are five things to know about IgA nephropathy.

1. Disease-modifying therapies for IgA nephropathy have become available only recently.

The past few years have brought development of the first disease-modifying therapies to reduce proteinuria for adults with primary IgA nephropathy who are at risk for rapid disease progression. In 2021, the US Food and Drug Administration (FDA) approved a targeted-release formulation of the corticosteroid budesonide for these patients. This formulation delivers the drug to the distal ileum, targeting Peyer patches — the site of IgA production — while minimizing the adverse effects associated with systemic corticosteroid therapy.

The FDA most recently approved sparsentan, a nonimmunosuppressive therapy that combines an endothelin type A receptor antagonist with an angiotensin II type 1 receptor antagonist, for the same indication in 2023.

In addition, several studies have reported benefits with the use of sodium-glucose cotransporter 2 (SGLT2) inhibitors in the treatment of patients with IgA nephropathy at high risk for progression, although this use is still investigational.

2. The most common sign in patients with IgA nephropathy is blood in the urine.

The most common clinical manifestation of IgA nephropathy is microscopic or gross hematuria. Hematuria is often recurrent and may follow upper respiratory tract or other infections. The presence of blood in the urine may be episodic and can vary in severity.

Proteinuria is another key feature of IgA nephropathy. It may range from mild to moderate and, in some cases, can even progress to nephrotic-range proteinuria. The level of proteinuria is an important indicator of disease severity and prognosis. Persistent and significant proteinuria may be associated with an increased risk for progression to chronic kidney disease.

3. Five histologic features are widely used to predict clinical outcomes.

The Oxford classification of IgA nephropathy, or MEST score, published in 2009, comprises four histologic features that are independent predictors of clinical outcome: mesangial and endocapillary hypercellularity, segmental glomerulosclerosis, and interstitial fibrosis/tubular atrophy. In 2017, the IgA Nephropathy Classification Working Group added glomerular crescent formation to the Oxford classification, to form the MEST-C score.

If any of these features are seen, the prognosis can generally be assumed to be poor. Proteinuria, hypertension, elevated creatinine, and a decreased estimated glomerular filtration rate are some of the other factors that can contribute to poor clinical outcomes in patients with IgA nephropathy.

4. IgA nephropathy can eventually progress to end-stage kidney disease.

Progressive kidney dysfunction can occur in some individuals with IgA nephropathy. This may manifest as a gradual decline in glomerular filtration rate, leading to chronic kidney disease over time. In addition, up to 20% of patients progress to end-stage kidney disease within 10 years. The risk for renal impairment varies among individuals, and certain clinical and histologic features may influence the prognosis.

Hypertension is a common complication of IgA nephropathy. The mechanisms underlying hypertension in IgA nephropathy are complex and may involve alterations in the renin-angiotensin-aldosterone system and salt-water balance. Controlling blood pressure is important in managing IgA nephropathy to help slow the progression of kidney damage.

5. Definitive diagnosis requires a renal biopsy.

There are currently no validated diagnostic serum or urine biomarkers for IgA nephropathy, which, according to KDIGO (Kidney Disease: Improving Global Outcomes), requires a renal biopsy to make a definitive diagnosis. The characteristic finding is the deposition of IgA in the glomeruli, typically in the mesangial area. The biopsy can also provide information about the degree of inflammation, scarring, and other histologic features that help guide treatment decisions and predict outcomes.

Dr. Alper, associate professor, department of medicine, section of nephrology, Tulane University School of Medicine, New Orleans, has disclosed no relevant financial relationships.

A version of this article appeared on Medscape.com.

The use of hair-straightening products containing glyoxylic acid is associated with a risk for acute kidney failure because of the accumulation of calcium oxalate crystals in the kidneys. The observation was made by a team of French researchers who tested the suspected straightening product on animals. The product is believed to be the cause of several episodes of renal damage in a young woman.

“The results on mice are striking,” said study author Emmanuel Letavernier, MD, a nephrologist at Tenon Hospital in Paris. “They develop extremely severe acute kidney failure within 24 hours of applying the straightening cream. Samples show the presence of calcium oxalate crystals in all renal tubules.”

Given the potential nephrotoxicity of glyoxylic acid through topical application, products containing this compound should be avoided and ideally withdrawn from the market, the researchers suggested in a letter published in The New England Journal of Medicine. The appropriate departments of the French Agency for Food, Environmental, and Occupational Health and Safety have been alerted, Dr. Letavernier added.
 

Replacing Formaldehyde

Glyoxylic acid has recently been introduced into certain cosmetic products (such as shampoo, styling lotion, and straightening products), often as a replacement for formaldehyde, which is irritating and possibly carcinogenic. Glyoxylic acid is praised for its smoothing qualities. However, it is recommended to avoid contact with the scalp.

Cases of renal complications could be underdiagnosed, according to the researchers, who are preparing a nationwide survey. Renal failure can be silent. Among the signs that should raise concern are “scalp irritation accompanied by nausea or vomiting after a hair salon visit,” said Dr. Letavernier.

Similar cases have already been reported in the literature. An Israeli team recently described 26 patients treated for acute renal injuries after hair straightening in hair salons. Biopsies revealed calcium oxalate crystals in the kidneys.

The Israeli researchers suspected an effect of glycolic acid, another substance found in many cosmetic products, including straightening products. However, they could not provide evidence.
 

Glycolic Acid Safe?

By conducting a second animal study, which should be published soon, Dr. Letavernier and his team were able to rule out this hypothesis. “Glycolic acid does not pose a problem. Unlike glyoxylic acid, the application of glycolic acid on the skin of mice does not induce the formation of oxalate crystals in the kidneys, nor acute kidney failure.”

The French clinical case reported in the correspondence concerns a 26-year-old woman with no prior health history who had three episodes of acute renal damage 1 year apart. It turned out that each episode occurred shortly after hair straightening at a hair salon in Marseille.

The patient reported feeling a burning sensation during the hair treatment. Scalp irritations appeared. She then experienced vomiting, diarrhea, fever, and back pain. Analyses revealed high levels of plasma creatinine during each episode, indicating renal failure.

A CT scan showed no signs of urinary tract obstruction. However, the patient had a small kidney stone. Further analysis revealed the presence of blood and leukocytes in the urine. But there was no proteinuria or urinary infection.
 

Chronic Renal Failure

After each episode, renal function rapidly improved. “The repetition of episodes of acute renal failure is, however, a major risk factor for developing chronic renal failure in the long term,” said Dr. Letavernier.

The cream used in the hair salon to straighten hair was retrieved by the researchers. It contained a significant amount of glyoxylic acid but no glycolic acid.

To explore its potential nephrotoxic effect, they conducted a study on 10 mice. The animals were divided into two groups to test on one side topical application of the product and a gel without active product (control group) on the other.

Mice exposed to the product had oxalate crystals in their urine, unlike mice in the control group. A scan confirmed calcium oxalate deposits in the kidneys. Plasma creatinine levels increased significantly after exposure to glyoxylic acid.

“After passing through the epidermis, glyoxylic acid is rapidly converted in the blood to glyoxylate. In the liver and probably in other organs, glyoxylate is metabolized to become oxalate, which upon contact with calcium in the urine forms calcium oxalate crystals,” explained the specialist.

Excess calcium oxalate crystals causing renal failure are observed in rare conditions such as primary hyperoxaluria, a genetic disease affecting liver metabolism, or enteric hyperoxaluria, which is linked to increased intestinal permeability to oxalate: an anion naturally found in certain plants.
 

This story was translated from the Medscape French edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article appeared on Medscape.com.

The use of hair-straightening products containing glyoxylic acid is associated with a risk for acute kidney failure because of the accumulation of calcium oxalate crystals in the kidneys. The observation was made by a team of French researchers who tested the suspected straightening product on animals. The product is believed to be the cause of several episodes of renal damage in a young woman.

“The results on mice are striking,” said study author Emmanuel Letavernier, MD, a nephrologist at Tenon Hospital in Paris. “They develop extremely severe acute kidney failure within 24 hours of applying the straightening cream. Samples show the presence of calcium oxalate crystals in all renal tubules.”

Given the potential nephrotoxicity of glyoxylic acid through topical application, products containing this compound should be avoided and ideally withdrawn from the market, the researchers suggested in a letter published in The New England Journal of Medicine. The appropriate departments of the French Agency for Food, Environmental, and Occupational Health and Safety have been alerted, Dr. Letavernier added.
 

Replacing Formaldehyde

Glyoxylic acid has recently been introduced into certain cosmetic products (such as shampoo, styling lotion, and straightening products), often as a replacement for formaldehyde, which is irritating and possibly carcinogenic. Glyoxylic acid is praised for its smoothing qualities. However, it is recommended to avoid contact with the scalp.

Cases of renal complications could be underdiagnosed, according to the researchers, who are preparing a nationwide survey. Renal failure can be silent. Among the signs that should raise concern are “scalp irritation accompanied by nausea or vomiting after a hair salon visit,” said Dr. Letavernier.

Similar cases have already been reported in the literature. An Israeli team recently described 26 patients treated for acute renal injuries after hair straightening in hair salons. Biopsies revealed calcium oxalate crystals in the kidneys.

The Israeli researchers suspected an effect of glycolic acid, another substance found in many cosmetic products, including straightening products. However, they could not provide evidence.
 

Glycolic Acid Safe?

By conducting a second animal study, which should be published soon, Dr. Letavernier and his team were able to rule out this hypothesis. “Glycolic acid does not pose a problem. Unlike glyoxylic acid, the application of glycolic acid on the skin of mice does not induce the formation of oxalate crystals in the kidneys, nor acute kidney failure.”

The French clinical case reported in the correspondence concerns a 26-year-old woman with no prior health history who had three episodes of acute renal damage 1 year apart. It turned out that each episode occurred shortly after hair straightening at a hair salon in Marseille.

The patient reported feeling a burning sensation during the hair treatment. Scalp irritations appeared. She then experienced vomiting, diarrhea, fever, and back pain. Analyses revealed high levels of plasma creatinine during each episode, indicating renal failure.

A CT scan showed no signs of urinary tract obstruction. However, the patient had a small kidney stone. Further analysis revealed the presence of blood and leukocytes in the urine. But there was no proteinuria or urinary infection.
 

Chronic Renal Failure

After each episode, renal function rapidly improved. “The repetition of episodes of acute renal failure is, however, a major risk factor for developing chronic renal failure in the long term,” said Dr. Letavernier.

The cream used in the hair salon to straighten hair was retrieved by the researchers. It contained a significant amount of glyoxylic acid but no glycolic acid.

To explore its potential nephrotoxic effect, they conducted a study on 10 mice. The animals were divided into two groups to test on one side topical application of the product and a gel without active product (control group) on the other.

Mice exposed to the product had oxalate crystals in their urine, unlike mice in the control group. A scan confirmed calcium oxalate deposits in the kidneys. Plasma creatinine levels increased significantly after exposure to glyoxylic acid.

“After passing through the epidermis, glyoxylic acid is rapidly converted in the blood to glyoxylate. In the liver and probably in other organs, glyoxylate is metabolized to become oxalate, which upon contact with calcium in the urine forms calcium oxalate crystals,” explained the specialist.

Excess calcium oxalate crystals causing renal failure are observed in rare conditions such as primary hyperoxaluria, a genetic disease affecting liver metabolism, or enteric hyperoxaluria, which is linked to increased intestinal permeability to oxalate: an anion naturally found in certain plants.
 

This story was translated from the Medscape French edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article appeared on Medscape.com.

The use of hair-straightening products containing glyoxylic acid is associated with a risk for acute kidney failure because of the accumulation of calcium oxalate crystals in the kidneys. The observation was made by a team of French researchers who tested the suspected straightening product on animals. The product is believed to be the cause of several episodes of renal damage in a young woman.

“The results on mice are striking,” said study author Emmanuel Letavernier, MD, a nephrologist at Tenon Hospital in Paris. “They develop extremely severe acute kidney failure within 24 hours of applying the straightening cream. Samples show the presence of calcium oxalate crystals in all renal tubules.”

Given the potential nephrotoxicity of glyoxylic acid through topical application, products containing this compound should be avoided and ideally withdrawn from the market, the researchers suggested in a letter published in The New England Journal of Medicine. The appropriate departments of the French Agency for Food, Environmental, and Occupational Health and Safety have been alerted, Dr. Letavernier added.
 

Replacing Formaldehyde

Glyoxylic acid has recently been introduced into certain cosmetic products (such as shampoo, styling lotion, and straightening products), often as a replacement for formaldehyde, which is irritating and possibly carcinogenic. Glyoxylic acid is praised for its smoothing qualities. However, it is recommended to avoid contact with the scalp.

Cases of renal complications could be underdiagnosed, according to the researchers, who are preparing a nationwide survey. Renal failure can be silent. Among the signs that should raise concern are “scalp irritation accompanied by nausea or vomiting after a hair salon visit,” said Dr. Letavernier.

Similar cases have already been reported in the literature. An Israeli team recently described 26 patients treated for acute renal injuries after hair straightening in hair salons. Biopsies revealed calcium oxalate crystals in the kidneys.

The Israeli researchers suspected an effect of glycolic acid, another substance found in many cosmetic products, including straightening products. However, they could not provide evidence.
 

Glycolic Acid Safe?

By conducting a second animal study, which should be published soon, Dr. Letavernier and his team were able to rule out this hypothesis. “Glycolic acid does not pose a problem. Unlike glyoxylic acid, the application of glycolic acid on the skin of mice does not induce the formation of oxalate crystals in the kidneys, nor acute kidney failure.”

The French clinical case reported in the correspondence concerns a 26-year-old woman with no prior health history who had three episodes of acute renal damage 1 year apart. It turned out that each episode occurred shortly after hair straightening at a hair salon in Marseille.

The patient reported feeling a burning sensation during the hair treatment. Scalp irritations appeared. She then experienced vomiting, diarrhea, fever, and back pain. Analyses revealed high levels of plasma creatinine during each episode, indicating renal failure.

A CT scan showed no signs of urinary tract obstruction. However, the patient had a small kidney stone. Further analysis revealed the presence of blood and leukocytes in the urine. But there was no proteinuria or urinary infection.
 

Chronic Renal Failure

After each episode, renal function rapidly improved. “The repetition of episodes of acute renal failure is, however, a major risk factor for developing chronic renal failure in the long term,” said Dr. Letavernier.

The cream used in the hair salon to straighten hair was retrieved by the researchers. It contained a significant amount of glyoxylic acid but no glycolic acid.

To explore its potential nephrotoxic effect, they conducted a study on 10 mice. The animals were divided into two groups to test on one side topical application of the product and a gel without active product (control group) on the other.

Mice exposed to the product had oxalate crystals in their urine, unlike mice in the control group. A scan confirmed calcium oxalate deposits in the kidneys. Plasma creatinine levels increased significantly after exposure to glyoxylic acid.

“After passing through the epidermis, glyoxylic acid is rapidly converted in the blood to glyoxylate. In the liver and probably in other organs, glyoxylate is metabolized to become oxalate, which upon contact with calcium in the urine forms calcium oxalate crystals,” explained the specialist.

Excess calcium oxalate crystals causing renal failure are observed in rare conditions such as primary hyperoxaluria, a genetic disease affecting liver metabolism, or enteric hyperoxaluria, which is linked to increased intestinal permeability to oxalate: an anion naturally found in certain plants.
 

This story was translated from the Medscape French edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article appeared on Medscape.com.

This transcript has been edited for clarity.

Welcome to Impact Factor, your weekly dose of commentary on a new medical study. I’m Dr F. Perry Wilson of the Yale School of Medicine.

In the early days of the pandemic, before we really understood what COVID was, two specialties in the hospital had a foreboding sense that something was very strange about this virus. The first was the pulmonologists, who noticed the striking levels of hypoxemia — low oxygen in the blood — and the rapidity with which patients who had previously been stable would crash in the intensive care unit.

The second, and I mark myself among this group, were the nephrologists. The dialysis machines stopped working right. I remember rounding on patients in the hospital who were on dialysis for kidney failure in the setting of severe COVID infection and seeing clots forming on the dialysis filters. Some patients could barely get in a full treatment because the filters would clog so quickly.

We knew it was worse than flu because of the mortality rates, but these oddities made us realize that it was different too — not just a particularly nasty respiratory virus but one that had effects on the body that we hadn’t really seen before.

Centers for Disease Control and Prevention

Worldometer

Annals of Internal Medicine

Dr. Wilson

Dr. Wilson

Dr. Wilson

Dr. Wilson

Dr. WIlson

Dr. F. Perry Wilson is associate professor of medicine and public health and director of the Clinical and Translational Research Accelerator at Yale University, New Haven, Conn. He has disclosed no relevant financial relationships.

A version of this article appeared on Medscape.com.

This transcript has been edited for clarity.

Welcome to Impact Factor, your weekly dose of commentary on a new medical study. I’m Dr F. Perry Wilson of the Yale School of Medicine.

In the early days of the pandemic, before we really understood what COVID was, two specialties in the hospital had a foreboding sense that something was very strange about this virus. The first was the pulmonologists, who noticed the striking levels of hypoxemia — low oxygen in the blood — and the rapidity with which patients who had previously been stable would crash in the intensive care unit.

The second, and I mark myself among this group, were the nephrologists. The dialysis machines stopped working right. I remember rounding on patients in the hospital who were on dialysis for kidney failure in the setting of severe COVID infection and seeing clots forming on the dialysis filters. Some patients could barely get in a full treatment because the filters would clog so quickly.

We knew it was worse than flu because of the mortality rates, but these oddities made us realize that it was different too — not just a particularly nasty respiratory virus but one that had effects on the body that we hadn’t really seen before.

Centers for Disease Control and Prevention

Worldometer

Annals of Internal Medicine

Dr. Wilson

Dr. Wilson

Dr. Wilson

Dr. Wilson

Dr. WIlson

Dr. F. Perry Wilson is associate professor of medicine and public health and director of the Clinical and Translational Research Accelerator at Yale University, New Haven, Conn. He has disclosed no relevant financial relationships.

A version of this article appeared on Medscape.com.

This transcript has been edited for clarity.

Welcome to Impact Factor, your weekly dose of commentary on a new medical study. I’m Dr F. Perry Wilson of the Yale School of Medicine.

In the early days of the pandemic, before we really understood what COVID was, two specialties in the hospital had a foreboding sense that something was very strange about this virus. The first was the pulmonologists, who noticed the striking levels of hypoxemia — low oxygen in the blood — and the rapidity with which patients who had previously been stable would crash in the intensive care unit.

The second, and I mark myself among this group, were the nephrologists. The dialysis machines stopped working right. I remember rounding on patients in the hospital who were on dialysis for kidney failure in the setting of severe COVID infection and seeing clots forming on the dialysis filters. Some patients could barely get in a full treatment because the filters would clog so quickly.

We knew it was worse than flu because of the mortality rates, but these oddities made us realize that it was different too — not just a particularly nasty respiratory virus but one that had effects on the body that we hadn’t really seen before.

Centers for Disease Control and Prevention

Worldometer

Annals of Internal Medicine

Dr. Wilson

Dr. Wilson

Dr. Wilson

Dr. Wilson

Dr. WIlson

Dr. F. Perry Wilson is associate professor of medicine and public health and director of the Clinical and Translational Research Accelerator at Yale University, New Haven, Conn. He has disclosed no relevant financial relationships.

A version of this article appeared on Medscape.com.

TOPLINE:

Metformin cuts the risk for diabetic nephropathy (DN) and major kidney and cardiovascular events in patients with newly diagnosed type 2 diabetes (T2D) across various renal function states.

METHODOLOGY:

Metformin is a first-line treatment in US and South Korean T2D management guidelines, except for patients with advanced chronic kidney disease (CKD) (stage, ≥ 4; estimated glomerular filtration rate [eGFR], < 30).

The study used data from the databases of three tertiary hospitals in South Korea to assess the effect of metformin on long-term renal and cardiovascular outcomes across various renal function states in patients with newly diagnosed T2D.

Four groups of treatment-control comparative cohorts were identified at each hospital: Patients who had not yet developed DN at T2D diagnosis (mean age in treatment and control cohorts, 61-65 years) and those with reduced renal function (CKD stages 3A, 3B, and 4).

Patients who continuously received metformin after T2D diagnosis and beyond the observation period were 1:1 propensity score matched with controls who were prescribed oral hypoglycemic agents other than metformin.

Primary outcomes were net major adverse cardiovascular events including strokes (MACEs) or in-hospital death and a composite of major adverse kidney events (MAKEs) or in-hospital death.

TAKEAWAY:

Among patients without DN at T2D diagnosis, the continuous use of metformin vs other oral hypoglycemic agents was associated with a lower risk for:

Overt DN (incidence rate ratio [IRR], 0.82; 95% CI, 0.71-0.95),

MACEs (IRR, 0.76; 95% CI, 0.64-0.92), and

MAKEs (IRR, 0.45; 95% CI, 0.33-0.62).

Compared with non-metformin or discontinued metformin use, the continuous use of metformin was associated with a lower risk for MACE across CKD stages 3A (IRR, 0.70; 95% CI, 0.57-0.87), 3B (IRR, 0.83; 95% CI, 0.74-0.93), and 4 (IRR, 0.71; 95% CI, 0.60-0.85).

Similarly, the risk for MAKE was lower among continuous metformin users than in nonusers or discontinuous metformin users across CKD stage 3A (IRR, 0.39; 95% CI, 0.35-0.43), 3B (IRR, 0.44; 95% CI, 0.40-0.48), and 4 (IRR, 0.45; 95% CI, 0.39-0.51).

IN PRACTICE:

“The significance of the current study is highlighted by its integration of real-world clinical data, which encompasses patients diagnosed with CDK4 [eGRF, 15-29 mL/min/1.73 m2], a group currently considered contraindicated,” the authors wrote.

SOURCE:

The study, led by Yongjin Yi, MD, PhD, Department of Internal Medicine, Dankook University College of Medicine, Cheonan-si, Republic of Korea, was published in Scientific Reports.

LIMITATIONS:

There may be a possibility of selection bias because of the retrospective and observational nature of this study. Despite achieving a 1:1 propensity score matching to address the confounding factors, some variables, such as serum albumin and A1c levels, remained unbalanced after matching. The paper did not include observation length or patient numbers, but in response to an email query from Medscape, Yi notes that in one hospital, the mean duration of observation for the control and treatment groups was about 6.5 years, and the total number in the treatment groups across data from three hospitals was 11,675, with the same number of matched controls.

DISCLOSURES:

This study was supported by a Young Investigator Research Grant from the Korean Society of Nephrology, a grant from the Seoul National University Bundang Hospital Research Fund, and the Bio&Medical Technology Development Program of the National Research Foundation funded by the Korean government. The authors disclosed no competing interests.

A version of this article appeared on Medscape.com.

TOPLINE:

Metformin cuts the risk for diabetic nephropathy (DN) and major kidney and cardiovascular events in patients with newly diagnosed type 2 diabetes (T2D) across various renal function states.

METHODOLOGY:

Metformin is a first-line treatment in US and South Korean T2D management guidelines, except for patients with advanced chronic kidney disease (CKD) (stage, ≥ 4; estimated glomerular filtration rate [eGFR], < 30).

The study used data from the databases of three tertiary hospitals in South Korea to assess the effect of metformin on long-term renal and cardiovascular outcomes across various renal function states in patients with newly diagnosed T2D.

Four groups of treatment-control comparative cohorts were identified at each hospital: Patients who had not yet developed DN at T2D diagnosis (mean age in treatment and control cohorts, 61-65 years) and those with reduced renal function (CKD stages 3A, 3B, and 4).

Patients who continuously received metformin after T2D diagnosis and beyond the observation period were 1:1 propensity score matched with controls who were prescribed oral hypoglycemic agents other than metformin.

Primary outcomes were net major adverse cardiovascular events including strokes (MACEs) or in-hospital death and a composite of major adverse kidney events (MAKEs) or in-hospital death.

TAKEAWAY:

Among patients without DN at T2D diagnosis, the continuous use of metformin vs other oral hypoglycemic agents was associated with a lower risk for:

Overt DN (incidence rate ratio [IRR], 0.82; 95% CI, 0.71-0.95),

MACEs (IRR, 0.76; 95% CI, 0.64-0.92), and

MAKEs (IRR, 0.45; 95% CI, 0.33-0.62).

Compared with non-metformin or discontinued metformin use, the continuous use of metformin was associated with a lower risk for MACE across CKD stages 3A (IRR, 0.70; 95% CI, 0.57-0.87), 3B (IRR, 0.83; 95% CI, 0.74-0.93), and 4 (IRR, 0.71; 95% CI, 0.60-0.85).

Similarly, the risk for MAKE was lower among continuous metformin users than in nonusers or discontinuous metformin users across CKD stage 3A (IRR, 0.39; 95% CI, 0.35-0.43), 3B (IRR, 0.44; 95% CI, 0.40-0.48), and 4 (IRR, 0.45; 95% CI, 0.39-0.51).

IN PRACTICE:

“The significance of the current study is highlighted by its integration of real-world clinical data, which encompasses patients diagnosed with CDK4 [eGRF, 15-29 mL/min/1.73 m2], a group currently considered contraindicated,” the authors wrote.

SOURCE:

The study, led by Yongjin Yi, MD, PhD, Department of Internal Medicine, Dankook University College of Medicine, Cheonan-si, Republic of Korea, was published in Scientific Reports.

LIMITATIONS:

There may be a possibility of selection bias because of the retrospective and observational nature of this study. Despite achieving a 1:1 propensity score matching to address the confounding factors, some variables, such as serum albumin and A1c levels, remained unbalanced after matching. The paper did not include observation length or patient numbers, but in response to an email query from Medscape, Yi notes that in one hospital, the mean duration of observation for the control and treatment groups was about 6.5 years, and the total number in the treatment groups across data from three hospitals was 11,675, with the same number of matched controls.

DISCLOSURES:

This study was supported by a Young Investigator Research Grant from the Korean Society of Nephrology, a grant from the Seoul National University Bundang Hospital Research Fund, and the Bio&Medical Technology Development Program of the National Research Foundation funded by the Korean government. The authors disclosed no competing interests.

A version of this article appeared on Medscape.com.

TOPLINE:

Metformin cuts the risk for diabetic nephropathy (DN) and major kidney and cardiovascular events in patients with newly diagnosed type 2 diabetes (T2D) across various renal function states.

METHODOLOGY:

Metformin is a first-line treatment in US and South Korean T2D management guidelines, except for patients with advanced chronic kidney disease (CKD) (stage, ≥ 4; estimated glomerular filtration rate [eGFR], < 30).

The study used data from the databases of three tertiary hospitals in South Korea to assess the effect of metformin on long-term renal and cardiovascular outcomes across various renal function states in patients with newly diagnosed T2D.

Four groups of treatment-control comparative cohorts were identified at each hospital: Patients who had not yet developed DN at T2D diagnosis (mean age in treatment and control cohorts, 61-65 years) and those with reduced renal function (CKD stages 3A, 3B, and 4).

Patients who continuously received metformin after T2D diagnosis and beyond the observation period were 1:1 propensity score matched with controls who were prescribed oral hypoglycemic agents other than metformin.

Primary outcomes were net major adverse cardiovascular events including strokes (MACEs) or in-hospital death and a composite of major adverse kidney events (MAKEs) or in-hospital death.

TAKEAWAY:

Among patients without DN at T2D diagnosis, the continuous use of metformin vs other oral hypoglycemic agents was associated with a lower risk for:

Overt DN (incidence rate ratio [IRR], 0.82; 95% CI, 0.71-0.95),

MACEs (IRR, 0.76; 95% CI, 0.64-0.92), and

MAKEs (IRR, 0.45; 95% CI, 0.33-0.62).

Compared with non-metformin or discontinued metformin use, the continuous use of metformin was associated with a lower risk for MACE across CKD stages 3A (IRR, 0.70; 95% CI, 0.57-0.87), 3B (IRR, 0.83; 95% CI, 0.74-0.93), and 4 (IRR, 0.71; 95% CI, 0.60-0.85).

Similarly, the risk for MAKE was lower among continuous metformin users than in nonusers or discontinuous metformin users across CKD stage 3A (IRR, 0.39; 95% CI, 0.35-0.43), 3B (IRR, 0.44; 95% CI, 0.40-0.48), and 4 (IRR, 0.45; 95% CI, 0.39-0.51).

IN PRACTICE:

“The significance of the current study is highlighted by its integration of real-world clinical data, which encompasses patients diagnosed with CDK4 [eGRF, 15-29 mL/min/1.73 m2], a group currently considered contraindicated,” the authors wrote.

SOURCE:

The study, led by Yongjin Yi, MD, PhD, Department of Internal Medicine, Dankook University College of Medicine, Cheonan-si, Republic of Korea, was published in Scientific Reports.

LIMITATIONS:

There may be a possibility of selection bias because of the retrospective and observational nature of this study. Despite achieving a 1:1 propensity score matching to address the confounding factors, some variables, such as serum albumin and A1c levels, remained unbalanced after matching. The paper did not include observation length or patient numbers, but in response to an email query from Medscape, Yi notes that in one hospital, the mean duration of observation for the control and treatment groups was about 6.5 years, and the total number in the treatment groups across data from three hospitals was 11,675, with the same number of matched controls.

DISCLOSURES:

This study was supported by a Young Investigator Research Grant from the Korean Society of Nephrology, a grant from the Seoul National University Bundang Hospital Research Fund, and the Bio&Medical Technology Development Program of the National Research Foundation funded by the Korean government. The authors disclosed no competing interests.

A version of this article appeared on Medscape.com.

The Pharmacovigilance Risk Assessment Committee (PRAC) of the European Medicines Agency (EMA) has issued a reminder to healthcare professionals regarding the potential serious adverse reactions associated with Paxlovid when administered in combination with specific immunosuppressants.

These immunosuppressants, encompassing calcineurin inhibitors (tacrolimus and ciclosporin) and mTOR inhibitors (everolimus and sirolimus), possess a narrow safe dosage range. They are recognized for their role in diminishing the activity of the immune system and are typically prescribed for autoimmune conditions and organ transplant recipients.

The highlighted risk arises due to drug-drug interactions, which can compromise the body’s ability to eliminate these medicines effectively.

Paxlovid, also known as nirmatrelvir with ritonavir, is an antiviral medication used to treat COVID-19 in adults who do not require supplemental oxygen and who are at an increased risk of progressing to severe COVID-19. It should be administered as soon as possible after a diagnosis of COVID-19 has been made and within 5 days of symptom onset.

Conditional marketing authorization for Paxlovid was granted across the European Union (EU) on January 28, 2022, and subsequently transitioned to full marketing authorization on February 24, 2023.

Developed by Pfizer, Paxlovid exhibited an 89% reduction in the risk for hospitalization or death among unvaccinated individuals in a phase 2-3 clinical trial. This led the National Institutes of Health to prioritize Paxlovid over other COVID-19 treatments. Subsequent real-world studies have affirmed its effectiveness, even among the vaccinated.

When combining Paxlovid with tacrolimus, ciclosporin, everolimus, or sirolimus, healthcare professionals need to actively monitor their blood levels. This proactive approach is essential to mitigate the risk for drug-drug interactions and potential serious reactions. They should collaborate with a multidisciplinary team of specialists to navigate the complexities of administering these medications concurrently.

Further, Paxlovid must not be coadministered with medications highly reliant on CYP3A liver enzymes for elimination, such as the immunosuppressant voclosporin. When administered together, there is a risk for these drugs interfering with each other’s metabolism, potentially leading to altered blood levels, reduced effectiveness, or an increased risk for adverse reactions.

After a thorough review, PRAC has highlighted potential serious adverse reactions, including fatal cases, due to drug interactions between Paxlovid and specified immunosuppressants. Thus, it issued a direct healthcare professional communication (DHPC) to emphasize the recognized risk for these interactions, as previously outlined in Paxlovid’s product information.

The DHPC for Paxlovid will undergo further evaluation by EMA’s Committee for Medicinal Products for Human Use and, upon adoption, will be disseminated to healthcare professionals. The communication plan will include publication on the DHPCs page and in national registers across EU Member States.

A version of this article appeared on Medscape.com.

The Pharmacovigilance Risk Assessment Committee (PRAC) of the European Medicines Agency (EMA) has issued a reminder to healthcare professionals regarding the potential serious adverse reactions associated with Paxlovid when administered in combination with specific immunosuppressants.

These immunosuppressants, encompassing calcineurin inhibitors (tacrolimus and ciclosporin) and mTOR inhibitors (everolimus and sirolimus), possess a narrow safe dosage range. They are recognized for their role in diminishing the activity of the immune system and are typically prescribed for autoimmune conditions and organ transplant recipients.

The highlighted risk arises due to drug-drug interactions, which can compromise the body’s ability to eliminate these medicines effectively.

Paxlovid, also known as nirmatrelvir with ritonavir, is an antiviral medication used to treat COVID-19 in adults who do not require supplemental oxygen and who are at an increased risk of progressing to severe COVID-19. It should be administered as soon as possible after a diagnosis of COVID-19 has been made and within 5 days of symptom onset.

Conditional marketing authorization for Paxlovid was granted across the European Union (EU) on January 28, 2022, and subsequently transitioned to full marketing authorization on February 24, 2023.

Developed by Pfizer, Paxlovid exhibited an 89% reduction in the risk for hospitalization or death among unvaccinated individuals in a phase 2-3 clinical trial. This led the National Institutes of Health to prioritize Paxlovid over other COVID-19 treatments. Subsequent real-world studies have affirmed its effectiveness, even among the vaccinated.

When combining Paxlovid with tacrolimus, ciclosporin, everolimus, or sirolimus, healthcare professionals need to actively monitor their blood levels. This proactive approach is essential to mitigate the risk for drug-drug interactions and potential serious reactions. They should collaborate with a multidisciplinary team of specialists to navigate the complexities of administering these medications concurrently.

Further, Paxlovid must not be coadministered with medications highly reliant on CYP3A liver enzymes for elimination, such as the immunosuppressant voclosporin. When administered together, there is a risk for these drugs interfering with each other’s metabolism, potentially leading to altered blood levels, reduced effectiveness, or an increased risk for adverse reactions.

After a thorough review, PRAC has highlighted potential serious adverse reactions, including fatal cases, due to drug interactions between Paxlovid and specified immunosuppressants. Thus, it issued a direct healthcare professional communication (DHPC) to emphasize the recognized risk for these interactions, as previously outlined in Paxlovid’s product information.

The DHPC for Paxlovid will undergo further evaluation by EMA’s Committee for Medicinal Products for Human Use and, upon adoption, will be disseminated to healthcare professionals. The communication plan will include publication on the DHPCs page and in national registers across EU Member States.

A version of this article appeared on Medscape.com.

The Pharmacovigilance Risk Assessment Committee (PRAC) of the European Medicines Agency (EMA) has issued a reminder to healthcare professionals regarding the potential serious adverse reactions associated with Paxlovid when administered in combination with specific immunosuppressants.

These immunosuppressants, encompassing calcineurin inhibitors (tacrolimus and ciclosporin) and mTOR inhibitors (everolimus and sirolimus), possess a narrow safe dosage range. They are recognized for their role in diminishing the activity of the immune system and are typically prescribed for autoimmune conditions and organ transplant recipients.

The highlighted risk arises due to drug-drug interactions, which can compromise the body’s ability to eliminate these medicines effectively.

Paxlovid, also known as nirmatrelvir with ritonavir, is an antiviral medication used to treat COVID-19 in adults who do not require supplemental oxygen and who are at an increased risk of progressing to severe COVID-19. It should be administered as soon as possible after a diagnosis of COVID-19 has been made and within 5 days of symptom onset.

Conditional marketing authorization for Paxlovid was granted across the European Union (EU) on January 28, 2022, and subsequently transitioned to full marketing authorization on February 24, 2023.

Developed by Pfizer, Paxlovid exhibited an 89% reduction in the risk for hospitalization or death among unvaccinated individuals in a phase 2-3 clinical trial. This led the National Institutes of Health to prioritize Paxlovid over other COVID-19 treatments. Subsequent real-world studies have affirmed its effectiveness, even among the vaccinated.

When combining Paxlovid with tacrolimus, ciclosporin, everolimus, or sirolimus, healthcare professionals need to actively monitor their blood levels. This proactive approach is essential to mitigate the risk for drug-drug interactions and potential serious reactions. They should collaborate with a multidisciplinary team of specialists to navigate the complexities of administering these medications concurrently.

Further, Paxlovid must not be coadministered with medications highly reliant on CYP3A liver enzymes for elimination, such as the immunosuppressant voclosporin. When administered together, there is a risk for these drugs interfering with each other’s metabolism, potentially leading to altered blood levels, reduced effectiveness, or an increased risk for adverse reactions.

After a thorough review, PRAC has highlighted potential serious adverse reactions, including fatal cases, due to drug interactions between Paxlovid and specified immunosuppressants. Thus, it issued a direct healthcare professional communication (DHPC) to emphasize the recognized risk for these interactions, as previously outlined in Paxlovid’s product information.

The DHPC for Paxlovid will undergo further evaluation by EMA’s Committee for Medicinal Products for Human Use and, upon adoption, will be disseminated to healthcare professionals. The communication plan will include publication on the DHPCs page and in national registers across EU Member States.

A version of this article appeared on Medscape.com.

Clinicians usually measure renal function by using surrogate markers because directly measuring glomerular filtration rate (GFR) is not routinely feasible in a clinical setting.^1,2 Creatinine (Cr) and cystatin C (CysC) are the 2 main surrogate molecules used to estimate GFR.³

Creatine is a molecule nonenzymatically converted into Cr, weighing only 113 Da in skeletal muscles.⁴ It is then filtered at the glomeruli and secreted at the proximal tubules of the kidneys. However, serum Cr (sCr) levels are affected by several factors, including age, biological sex, liver function, diet, and muscle mass.⁵ Historically, sCr levels also are affected by race.⁵ In an early study of factors affecting accurate GFR, researchers reported that self-identified African American patients had a 16% higher GFR than those who did not when using Cr.⁶ Despite this, the inclusion of Cr on a basic metabolic panel has allowed automatic reporting of an estimated GFR using sCr (eGFR_Cr) to be readily available.⁷

In comparison to Cr, CysC is an endogenous protein weighing 13 kDa produced by all nucleated cells.^8,9 CysC is filtered by the kidney at the glomeruli and completely reabsorbed and catabolized by epithelial cells at the proximal tubule.⁹ Since production is not dependent on skeletal muscle, there are fewer physiological impacts on serum concentration of CysC. Levels of CysC may be elevated by factors shown in the Table.

Estimating Glomerular Filtration Rates

Multiple equations were developed to mitigate the impact of extraneous factors on the accuracy of an eGFR_Cr. The first widely used equation that included a variable adjustment for race was the Modification of Diet in Renal Disease study, presented in 2006.¹⁰ The equation increased the accuracy of eGFR_Cr further by adjusting for sex and age. It was followed by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation in 2009, which was more accurate at higher GFR levels.¹¹

CysC was simultaneously studied as an alternative to Cr with multiple equation iterations shown to be viable in various populations as early as 2003.^12-15 However, it was not until 2012 that an equation for the use of CysC was offered for widespread use as an alternative to Cr alongside further refinement of the CKD-EPI equation for Cr.¹⁶ A new formula was presented in 2021 to use both sCr and serum CysC levels to obtain a more accurate estimation of GFR.¹⁷ Research continues its effort to accurately estimate GFR for diagnosing kidney disease and assessing comorbidities relating to decreased kidney function.³

All historical equations attempted to mitigate the potential impact of race on sCr level when calculating eGFR_Crby assigning a separate variable for African American patients. As an unintended adverse effect, these equations may have led to discrimination by having a different equation for African American patients.¹⁸ Moreover, these Cr-based equations remain less accurate in patients with varied muscle mass, such as older patients, bodybuilders, athletes, and individuals with varied extremes of daily protein intake.^1,8,9,19Several medications can also directly affect Cr clearance, reducing its ability to act as a surrogate for kidney function.¹In this case report, we discuss an African American patient with high muscle mass and protein intake who was initially diagnosed with kidney disease based on an elevated Cr and found to be misdiagnosed based on the use of CysC for a more accurate GFR estimation.

A 35-year-old African American man serving in the military and recently diagnosed with HIV was referred to a nephrology clinic for further evaluation of an acute elevation in sCr. Before treatment for HIV, a brief record review showed a baseline Cr of about 1.3 mg/dL, with an eGFR_Cr of 75 mL/min/1.73 m².²⁰ In the same month, the patient was prescribed bictegravir/emtricitabine/tenofovir alafenamide, an HIV drug with nephrotoxic potential.²¹ The patient's total viral load remained low, and CD4 count remained > 500 after initiation of the HIV treatment. He was in his normal state of health and had no known contributory history before his HIV diagnosis. Cr readings peaked at 1.83 mg/dL after starting the HIV treatment and remained elevated to 1.73 mg/dL over the next few months, corresponding to CKD stage 3A. Because bictegravir/emtricitabine/tenofovir alafenamide is cleared by the kidneys and has a nephrotoxic profile, the clinical care team considered dosage adjustment or a medication switch given his observed elevated eGFR_Cr based on the CKD-EPI 2021 equation for Cr alone. It was also noted that the patient had a similar Cr spike to 1.83 mg/dL in 2018 without any identifiable renal insult or symptoms (Figure).

Diagnostic Evaluation

The primary care team ordered a renal ultrasound and referred the patient to the nephrology clinic. The nephrologist ordered the following laboratory studies: urine microalbumin to Cr ratio, basic metabolic panel (BMP), comprehensive metabolic panel (CMP), urinalysis, urine protein, urine Cr, parathyroid hormone level, hemoglobin A_1c, complement component 3/4 panels, antinuclear and antineutrophil cytoplasmic antibodies titers, glomerular basement membrane antibody titer, urine light chains, serum protein electrophoresis, κ/λ ratio, viral hepatitis panel, and rapid plasma reagin testing. Much of this laboratory evaluation served to rule out any secondary causes of kidney disease, including autoimmune disease, monoclonal or polyclonal gammopathies, diabetic nephropathy or glomerulosclerosis, and nephrotic or nephritic syndromes.

All laboratory studies returned within normal limits; no proteinuria was discovered on urinalysis, and no abnormalities were visualized on renal ultrasound. Bictegravir/emtricitabine/tenofovir alafenamide nephrotoxicity was highest among the differential diagnoses due to the timing of Cr elevation coinciding with the initiation of the medications. The patient's CysC level was 0.85 mg/dL with a calculated eGFR_Cys of 125 mL/min/1.73 m². The calculated sCR and serum cystatin C (eGFR_Cr-Cys) using the new 2021 equation and when adjusting for body surface area placed his eGFR at 92 mL/min/1.73 m².²⁰

The patient’s eGFR_Cysreassured the care team that the patient’s renal function was not acutely or chronically impacted by bictegravir/emtricitabine/tenofovir alafenamide, resulting in avoidance of unnecessary dosage adjustment or discontinuation of the HIV treatment. The patient reported a chronic habit of protein and creatine supplementation and bodybuilding, which likely further compounded the discrepancy between eGFR_Cr and eGFR_Cys and explained his previous elevation in Cr in 2018.

Follow-up

The patient underwent serial monitoring that revealed a stable Cr and unremarkable eGFR, ruling out CKD. There has been no evidence of worsening kidney disease to date, and the patient remained on his initial HIV regimen.

This case shows the importance of using CysC as an alternative or confirmatory marker compared with sCr to estimate GFR in patients with high muscle mass and/or high creatine intake, such as many in the US Department of Defense (DoD) and US Department of Veterans Affairs (VA) patient populations. In the presented case, recorded Cr levels climbed from baseline Cr with the initiation of bictegravir/emtricitabine/tenofovir alafenamide. This raised the concern that HIV treatment was leading to the development of kidney damage.²²

Diagnosis of kidney disease as opposed to the normal decline of eGFR with age in individuals without intrinsic CKD requires GFR ≥ 60 mL/min/1.73 m² with kidney damage (proteinuria or radiological abnormalities, etc) or GFR < 135 to 140 mL/min/1.73 m²minus the patient’s age in years.²³ The patient’s Cr peak at 1.83 mg/dL in 2018 led to an inappropriate diagnosis of kidney disease stage 3a based on an eGFR_Cr (2021 equation) of 52 mL/min/1.73 m² when not corrected for body surface area.²⁰ However, using the new 2021 equation using both Cr and CysC, the patient’s eGFR_Cr-Cyswas 92 mL/min/1.73 m² after a correction for body surface area.

The 2009 CKD-EPI recommended the calculation of eGFR based on SCr concentration using age, sex, and race while the 2021 CKD-EPI recommended the exclusion of race.³ Both equations are less accurate in African American patients, individuals taking medications that interfere with Cr secretion and assay, and patients taking creatine supplements, high daily protein intake, or with high muscle mass.⁷ These settings result in a decreased eGFR_Cr without corresponding eGFR_Cys changes. Using SCr and CysC together, the eGFR_Cr-Cys yields improved concordance to measured GFR across race groups compared to GFR estimation based on Cr alone, which can avoid unnecessary expensive diagnostic workup, inappropriate kidney disease diagnosis, incorrect dosing of drugs, and accurately represent the military readiness of patients. Interestingly, in African American patients with recently diagnosed HIV, CKD-EPI using both Cr and CysC without race inclusion led to only a 2.9% overestimation of GFR and was the only equation with no statistically significant bias compared with measured GFR.²⁴

A March 2023 case involving an otherwise healthy 26-year-old male active-duty US Navy member with a history of excessive protein supplement intake and intense exercise < 24 hours before laboratory work was diagnosed with CKD after a measured Cr of 16 mg/dL and an eGFR_Cr of 4 mL/min/1.73 m² without any other evidence of kidney disease. His CysC remained within normal limits, resulting in a normal eGFR_Cys of 121 mL/min/1.73 m², indicating no CKD. His Cr and eGFR recovered 10 days after his clinic visit and cessation of his supplement intake. These findings may not be uncommon given that 65% of active-duty military use protein supplements and 38% use other performance-enhancing supplements, such as creatine, according to a study.²⁵

Unfortunately, the BMP/CMP traditionally used at VA centers use the eGFR_Cr equation, and it is unknown how many primary care practitioners recognize the limitations of these metabolic panels on accurate estimation of kidney function. However, in 2022 an expert panel including VA physicians recommended the immediate use of eGFR_Cr-Cys or eGFR_Cys for confirmatory testing and potentially screening of CKD.²⁶ A small number of VAs have since adopted this recommendation, which should lead to fewer misdiagnoses among US military members as clinicians should now have access to more accurate measurements of GFR.

The VA spends about $18 billion (excluding dialysis) for care for 1.1 to 2.5 million VA patients with CKD.²⁷ The majority of these diagnoses were undoubtedly made using the eGFR_Cr equation, raising the question of how many may be misdiagnosed. Assessment with CysC is currently relatively expensive, but it will likely become more affordable as the use of CysC as a confirmatory test increases.⁵ The cost of a sCr test is about $2.50, while CysC costs about $10.60, with variation from laboratory to laboratory.²⁸ By comparison, a renal ultrasound costs $99 to $140 for uninsured patients.²⁹ Furthermore, the cost of CysC testing is likely to trend downward as more facilities adopt the use of CysC measurements, which can be run on the same analytical equipment currently used for Cr measurements. Currently, most laboratories do not have established assays to use in-house and thus require CysC to be sent out to a laboratory, which increases result time and makes Cr a more attractive option. As more laboratories adopt assays for CysC, the cost of reagents will further decrease.

Given such considerations, confirmation testing of kidney function with CysC in specific patient populations with decreased eGFR_Cr without other features of CKD can offer great medical and financial benefits. A 2023 KDIGO report noted that many individuals may be mistakenly diagnosed with CKD when using eGFR_Cr.³ KDIGO noted that a 2013 meta-analysis of 90,000 individuals found that with a Cr-based eGFR of 45 to 59 mL/min/1.73 m² (42%) had a CysC-based eGFR of ≥ 60 mL/min/1.73 m². An eGFR_Cr of 45 to 59 represents 54% of all patients with CKD, amounting to millions of people (including current and former military personnel).^3,29-31 Correcting a misdiagnosis of CKD would bring significant relief to patients and save millions in health care spending.

Conclusions

In patients who meet CKD criteria using eGFR_Cr but without other features of CKD, we recommend using confirmatory CysC levels and the eGFR_Cr-Cys equation. This will align care with the KDIGO guidelines and could be a cost-effective step toward improving military patient care. Further work in this area should focus on determining the knowledge gaps in primary care practitioners’ understanding of the limits of eGFR_Cr, the potential mitigation of concomitant CysC testing in equivocal CKD cases, and the cost-effectiveness and increased utilization of CysC.

Clinicians usually measure renal function by using surrogate markers because directly measuring glomerular filtration rate (GFR) is not routinely feasible in a clinical setting.^1,2 Creatinine (Cr) and cystatin C (CysC) are the 2 main surrogate molecules used to estimate GFR.³

Creatine is a molecule nonenzymatically converted into Cr, weighing only 113 Da in skeletal muscles.⁴ It is then filtered at the glomeruli and secreted at the proximal tubules of the kidneys. However, serum Cr (sCr) levels are affected by several factors, including age, biological sex, liver function, diet, and muscle mass.⁵ Historically, sCr levels also are affected by race.⁵ In an early study of factors affecting accurate GFR, researchers reported that self-identified African American patients had a 16% higher GFR than those who did not when using Cr.⁶ Despite this, the inclusion of Cr on a basic metabolic panel has allowed automatic reporting of an estimated GFR using sCr (eGFR_Cr) to be readily available.⁷

In comparison to Cr, CysC is an endogenous protein weighing 13 kDa produced by all nucleated cells.^8,9 CysC is filtered by the kidney at the glomeruli and completely reabsorbed and catabolized by epithelial cells at the proximal tubule.⁹ Since production is not dependent on skeletal muscle, there are fewer physiological impacts on serum concentration of CysC. Levels of CysC may be elevated by factors shown in the Table.

Estimating Glomerular Filtration Rates

Multiple equations were developed to mitigate the impact of extraneous factors on the accuracy of an eGFR_Cr. The first widely used equation that included a variable adjustment for race was the Modification of Diet in Renal Disease study, presented in 2006.¹⁰ The equation increased the accuracy of eGFR_Cr further by adjusting for sex and age. It was followed by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation in 2009, which was more accurate at higher GFR levels.¹¹

CysC was simultaneously studied as an alternative to Cr with multiple equation iterations shown to be viable in various populations as early as 2003.^12-15 However, it was not until 2012 that an equation for the use of CysC was offered for widespread use as an alternative to Cr alongside further refinement of the CKD-EPI equation for Cr.¹⁶ A new formula was presented in 2021 to use both sCr and serum CysC levels to obtain a more accurate estimation of GFR.¹⁷ Research continues its effort to accurately estimate GFR for diagnosing kidney disease and assessing comorbidities relating to decreased kidney function.³

All historical equations attempted to mitigate the potential impact of race on sCr level when calculating eGFR_Crby assigning a separate variable for African American patients. As an unintended adverse effect, these equations may have led to discrimination by having a different equation for African American patients.¹⁸ Moreover, these Cr-based equations remain less accurate in patients with varied muscle mass, such as older patients, bodybuilders, athletes, and individuals with varied extremes of daily protein intake.^1,8,9,19Several medications can also directly affect Cr clearance, reducing its ability to act as a surrogate for kidney function.¹In this case report, we discuss an African American patient with high muscle mass and protein intake who was initially diagnosed with kidney disease based on an elevated Cr and found to be misdiagnosed based on the use of CysC for a more accurate GFR estimation.

A 35-year-old African American man serving in the military and recently diagnosed with HIV was referred to a nephrology clinic for further evaluation of an acute elevation in sCr. Before treatment for HIV, a brief record review showed a baseline Cr of about 1.3 mg/dL, with an eGFR_Cr of 75 mL/min/1.73 m².²⁰ In the same month, the patient was prescribed bictegravir/emtricitabine/tenofovir alafenamide, an HIV drug with nephrotoxic potential.²¹ The patient's total viral load remained low, and CD4 count remained > 500 after initiation of the HIV treatment. He was in his normal state of health and had no known contributory history before his HIV diagnosis. Cr readings peaked at 1.83 mg/dL after starting the HIV treatment and remained elevated to 1.73 mg/dL over the next few months, corresponding to CKD stage 3A. Because bictegravir/emtricitabine/tenofovir alafenamide is cleared by the kidneys and has a nephrotoxic profile, the clinical care team considered dosage adjustment or a medication switch given his observed elevated eGFR_Cr based on the CKD-EPI 2021 equation for Cr alone. It was also noted that the patient had a similar Cr spike to 1.83 mg/dL in 2018 without any identifiable renal insult or symptoms (Figure).

Diagnostic Evaluation

The primary care team ordered a renal ultrasound and referred the patient to the nephrology clinic. The nephrologist ordered the following laboratory studies: urine microalbumin to Cr ratio, basic metabolic panel (BMP), comprehensive metabolic panel (CMP), urinalysis, urine protein, urine Cr, parathyroid hormone level, hemoglobin A_1c, complement component 3/4 panels, antinuclear and antineutrophil cytoplasmic antibodies titers, glomerular basement membrane antibody titer, urine light chains, serum protein electrophoresis, κ/λ ratio, viral hepatitis panel, and rapid plasma reagin testing. Much of this laboratory evaluation served to rule out any secondary causes of kidney disease, including autoimmune disease, monoclonal or polyclonal gammopathies, diabetic nephropathy or glomerulosclerosis, and nephrotic or nephritic syndromes.

All laboratory studies returned within normal limits; no proteinuria was discovered on urinalysis, and no abnormalities were visualized on renal ultrasound. Bictegravir/emtricitabine/tenofovir alafenamide nephrotoxicity was highest among the differential diagnoses due to the timing of Cr elevation coinciding with the initiation of the medications. The patient's CysC level was 0.85 mg/dL with a calculated eGFR_Cys of 125 mL/min/1.73 m². The calculated sCR and serum cystatin C (eGFR_Cr-Cys) using the new 2021 equation and when adjusting for body surface area placed his eGFR at 92 mL/min/1.73 m².²⁰

The patient’s eGFR_Cysreassured the care team that the patient’s renal function was not acutely or chronically impacted by bictegravir/emtricitabine/tenofovir alafenamide, resulting in avoidance of unnecessary dosage adjustment or discontinuation of the HIV treatment. The patient reported a chronic habit of protein and creatine supplementation and bodybuilding, which likely further compounded the discrepancy between eGFR_Cr and eGFR_Cys and explained his previous elevation in Cr in 2018.

Follow-up

The patient underwent serial monitoring that revealed a stable Cr and unremarkable eGFR, ruling out CKD. There has been no evidence of worsening kidney disease to date, and the patient remained on his initial HIV regimen.

This case shows the importance of using CysC as an alternative or confirmatory marker compared with sCr to estimate GFR in patients with high muscle mass and/or high creatine intake, such as many in the US Department of Defense (DoD) and US Department of Veterans Affairs (VA) patient populations. In the presented case, recorded Cr levels climbed from baseline Cr with the initiation of bictegravir/emtricitabine/tenofovir alafenamide. This raised the concern that HIV treatment was leading to the development of kidney damage.²²

Diagnosis of kidney disease as opposed to the normal decline of eGFR with age in individuals without intrinsic CKD requires GFR ≥ 60 mL/min/1.73 m² with kidney damage (proteinuria or radiological abnormalities, etc) or GFR < 135 to 140 mL/min/1.73 m²minus the patient’s age in years.²³ The patient’s Cr peak at 1.83 mg/dL in 2018 led to an inappropriate diagnosis of kidney disease stage 3a based on an eGFR_Cr (2021 equation) of 52 mL/min/1.73 m² when not corrected for body surface area.²⁰ However, using the new 2021 equation using both Cr and CysC, the patient’s eGFR_Cr-Cyswas 92 mL/min/1.73 m² after a correction for body surface area.

The 2009 CKD-EPI recommended the calculation of eGFR based on SCr concentration using age, sex, and race while the 2021 CKD-EPI recommended the exclusion of race.³ Both equations are less accurate in African American patients, individuals taking medications that interfere with Cr secretion and assay, and patients taking creatine supplements, high daily protein intake, or with high muscle mass.⁷ These settings result in a decreased eGFR_Cr without corresponding eGFR_Cys changes. Using SCr and CysC together, the eGFR_Cr-Cys yields improved concordance to measured GFR across race groups compared to GFR estimation based on Cr alone, which can avoid unnecessary expensive diagnostic workup, inappropriate kidney disease diagnosis, incorrect dosing of drugs, and accurately represent the military readiness of patients. Interestingly, in African American patients with recently diagnosed HIV, CKD-EPI using both Cr and CysC without race inclusion led to only a 2.9% overestimation of GFR and was the only equation with no statistically significant bias compared with measured GFR.²⁴

A March 2023 case involving an otherwise healthy 26-year-old male active-duty US Navy member with a history of excessive protein supplement intake and intense exercise < 24 hours before laboratory work was diagnosed with CKD after a measured Cr of 16 mg/dL and an eGFR_Cr of 4 mL/min/1.73 m² without any other evidence of kidney disease. His CysC remained within normal limits, resulting in a normal eGFR_Cys of 121 mL/min/1.73 m², indicating no CKD. His Cr and eGFR recovered 10 days after his clinic visit and cessation of his supplement intake. These findings may not be uncommon given that 65% of active-duty military use protein supplements and 38% use other performance-enhancing supplements, such as creatine, according to a study.²⁵

Unfortunately, the BMP/CMP traditionally used at VA centers use the eGFR_Cr equation, and it is unknown how many primary care practitioners recognize the limitations of these metabolic panels on accurate estimation of kidney function. However, in 2022 an expert panel including VA physicians recommended the immediate use of eGFR_Cr-Cys or eGFR_Cys for confirmatory testing and potentially screening of CKD.²⁶ A small number of VAs have since adopted this recommendation, which should lead to fewer misdiagnoses among US military members as clinicians should now have access to more accurate measurements of GFR.

The VA spends about $18 billion (excluding dialysis) for care for 1.1 to 2.5 million VA patients with CKD.²⁷ The majority of these diagnoses were undoubtedly made using the eGFR_Cr equation, raising the question of how many may be misdiagnosed. Assessment with CysC is currently relatively expensive, but it will likely become more affordable as the use of CysC as a confirmatory test increases.⁵ The cost of a sCr test is about $2.50, while CysC costs about $10.60, with variation from laboratory to laboratory.²⁸ By comparison, a renal ultrasound costs $99 to $140 for uninsured patients.²⁹ Furthermore, the cost of CysC testing is likely to trend downward as more facilities adopt the use of CysC measurements, which can be run on the same analytical equipment currently used for Cr measurements. Currently, most laboratories do not have established assays to use in-house and thus require CysC to be sent out to a laboratory, which increases result time and makes Cr a more attractive option. As more laboratories adopt assays for CysC, the cost of reagents will further decrease.

Given such considerations, confirmation testing of kidney function with CysC in specific patient populations with decreased eGFR_Cr without other features of CKD can offer great medical and financial benefits. A 2023 KDIGO report noted that many individuals may be mistakenly diagnosed with CKD when using eGFR_Cr.³ KDIGO noted that a 2013 meta-analysis of 90,000 individuals found that with a Cr-based eGFR of 45 to 59 mL/min/1.73 m² (42%) had a CysC-based eGFR of ≥ 60 mL/min/1.73 m². An eGFR_Cr of 45 to 59 represents 54% of all patients with CKD, amounting to millions of people (including current and former military personnel).^3,29-31 Correcting a misdiagnosis of CKD would bring significant relief to patients and save millions in health care spending.

Conclusions

In patients who meet CKD criteria using eGFR_Cr but without other features of CKD, we recommend using confirmatory CysC levels and the eGFR_Cr-Cys equation. This will align care with the KDIGO guidelines and could be a cost-effective step toward improving military patient care. Further work in this area should focus on determining the knowledge gaps in primary care practitioners’ understanding of the limits of eGFR_Cr, the potential mitigation of concomitant CysC testing in equivocal CKD cases, and the cost-effectiveness and increased utilization of CysC.

Clinicians usually measure renal function by using surrogate markers because directly measuring glomerular filtration rate (GFR) is not routinely feasible in a clinical setting.^1,2 Creatinine (Cr) and cystatin C (CysC) are the 2 main surrogate molecules used to estimate GFR.³

Creatine is a molecule nonenzymatically converted into Cr, weighing only 113 Da in skeletal muscles.⁴ It is then filtered at the glomeruli and secreted at the proximal tubules of the kidneys. However, serum Cr (sCr) levels are affected by several factors, including age, biological sex, liver function, diet, and muscle mass.⁵ Historically, sCr levels also are affected by race.⁵ In an early study of factors affecting accurate GFR, researchers reported that self-identified African American patients had a 16% higher GFR than those who did not when using Cr.⁶ Despite this, the inclusion of Cr on a basic metabolic panel has allowed automatic reporting of an estimated GFR using sCr (eGFR_Cr) to be readily available.⁷

In comparison to Cr, CysC is an endogenous protein weighing 13 kDa produced by all nucleated cells.^8,9 CysC is filtered by the kidney at the glomeruli and completely reabsorbed and catabolized by epithelial cells at the proximal tubule.⁹ Since production is not dependent on skeletal muscle, there are fewer physiological impacts on serum concentration of CysC. Levels of CysC may be elevated by factors shown in the Table.

Estimating Glomerular Filtration Rates

Multiple equations were developed to mitigate the impact of extraneous factors on the accuracy of an eGFR_Cr. The first widely used equation that included a variable adjustment for race was the Modification of Diet in Renal Disease study, presented in 2006.¹⁰ The equation increased the accuracy of eGFR_Cr further by adjusting for sex and age. It was followed by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation in 2009, which was more accurate at higher GFR levels.¹¹

CysC was simultaneously studied as an alternative to Cr with multiple equation iterations shown to be viable in various populations as early as 2003.^12-15 However, it was not until 2012 that an equation for the use of CysC was offered for widespread use as an alternative to Cr alongside further refinement of the CKD-EPI equation for Cr.¹⁶ A new formula was presented in 2021 to use both sCr and serum CysC levels to obtain a more accurate estimation of GFR.¹⁷ Research continues its effort to accurately estimate GFR for diagnosing kidney disease and assessing comorbidities relating to decreased kidney function.³

All historical equations attempted to mitigate the potential impact of race on sCr level when calculating eGFR_Crby assigning a separate variable for African American patients. As an unintended adverse effect, these equations may have led to discrimination by having a different equation for African American patients.¹⁸ Moreover, these Cr-based equations remain less accurate in patients with varied muscle mass, such as older patients, bodybuilders, athletes, and individuals with varied extremes of daily protein intake.^1,8,9,19Several medications can also directly affect Cr clearance, reducing its ability to act as a surrogate for kidney function.¹In this case report, we discuss an African American patient with high muscle mass and protein intake who was initially diagnosed with kidney disease based on an elevated Cr and found to be misdiagnosed based on the use of CysC for a more accurate GFR estimation.

A 35-year-old African American man serving in the military and recently diagnosed with HIV was referred to a nephrology clinic for further evaluation of an acute elevation in sCr. Before treatment for HIV, a brief record review showed a baseline Cr of about 1.3 mg/dL, with an eGFR_Cr of 75 mL/min/1.73 m².²⁰ In the same month, the patient was prescribed bictegravir/emtricitabine/tenofovir alafenamide, an HIV drug with nephrotoxic potential.²¹ The patient's total viral load remained low, and CD4 count remained > 500 after initiation of the HIV treatment. He was in his normal state of health and had no known contributory history before his HIV diagnosis. Cr readings peaked at 1.83 mg/dL after starting the HIV treatment and remained elevated to 1.73 mg/dL over the next few months, corresponding to CKD stage 3A. Because bictegravir/emtricitabine/tenofovir alafenamide is cleared by the kidneys and has a nephrotoxic profile, the clinical care team considered dosage adjustment or a medication switch given his observed elevated eGFR_Cr based on the CKD-EPI 2021 equation for Cr alone. It was also noted that the patient had a similar Cr spike to 1.83 mg/dL in 2018 without any identifiable renal insult or symptoms (Figure).

Diagnostic Evaluation

The primary care team ordered a renal ultrasound and referred the patient to the nephrology clinic. The nephrologist ordered the following laboratory studies: urine microalbumin to Cr ratio, basic metabolic panel (BMP), comprehensive metabolic panel (CMP), urinalysis, urine protein, urine Cr, parathyroid hormone level, hemoglobin A_1c, complement component 3/4 panels, antinuclear and antineutrophil cytoplasmic antibodies titers, glomerular basement membrane antibody titer, urine light chains, serum protein electrophoresis, κ/λ ratio, viral hepatitis panel, and rapid plasma reagin testing. Much of this laboratory evaluation served to rule out any secondary causes of kidney disease, including autoimmune disease, monoclonal or polyclonal gammopathies, diabetic nephropathy or glomerulosclerosis, and nephrotic or nephritic syndromes.

All laboratory studies returned within normal limits; no proteinuria was discovered on urinalysis, and no abnormalities were visualized on renal ultrasound. Bictegravir/emtricitabine/tenofovir alafenamide nephrotoxicity was highest among the differential diagnoses due to the timing of Cr elevation coinciding with the initiation of the medications. The patient's CysC level was 0.85 mg/dL with a calculated eGFR_Cys of 125 mL/min/1.73 m². The calculated sCR and serum cystatin C (eGFR_Cr-Cys) using the new 2021 equation and when adjusting for body surface area placed his eGFR at 92 mL/min/1.73 m².²⁰

The patient’s eGFR_Cysreassured the care team that the patient’s renal function was not acutely or chronically impacted by bictegravir/emtricitabine/tenofovir alafenamide, resulting in avoidance of unnecessary dosage adjustment or discontinuation of the HIV treatment. The patient reported a chronic habit of protein and creatine supplementation and bodybuilding, which likely further compounded the discrepancy between eGFR_Cr and eGFR_Cys and explained his previous elevation in Cr in 2018.

Follow-up

The patient underwent serial monitoring that revealed a stable Cr and unremarkable eGFR, ruling out CKD. There has been no evidence of worsening kidney disease to date, and the patient remained on his initial HIV regimen.

This case shows the importance of using CysC as an alternative or confirmatory marker compared with sCr to estimate GFR in patients with high muscle mass and/or high creatine intake, such as many in the US Department of Defense (DoD) and US Department of Veterans Affairs (VA) patient populations. In the presented case, recorded Cr levels climbed from baseline Cr with the initiation of bictegravir/emtricitabine/tenofovir alafenamide. This raised the concern that HIV treatment was leading to the development of kidney damage.²²

Diagnosis of kidney disease as opposed to the normal decline of eGFR with age in individuals without intrinsic CKD requires GFR ≥ 60 mL/min/1.73 m² with kidney damage (proteinuria or radiological abnormalities, etc) or GFR < 135 to 140 mL/min/1.73 m²minus the patient’s age in years.²³ The patient’s Cr peak at 1.83 mg/dL in 2018 led to an inappropriate diagnosis of kidney disease stage 3a based on an eGFR_Cr (2021 equation) of 52 mL/min/1.73 m² when not corrected for body surface area.²⁰ However, using the new 2021 equation using both Cr and CysC, the patient’s eGFR_Cr-Cyswas 92 mL/min/1.73 m² after a correction for body surface area.

The 2009 CKD-EPI recommended the calculation of eGFR based on SCr concentration using age, sex, and race while the 2021 CKD-EPI recommended the exclusion of race.³ Both equations are less accurate in African American patients, individuals taking medications that interfere with Cr secretion and assay, and patients taking creatine supplements, high daily protein intake, or with high muscle mass.⁷ These settings result in a decreased eGFR_Cr without corresponding eGFR_Cys changes. Using SCr and CysC together, the eGFR_Cr-Cys yields improved concordance to measured GFR across race groups compared to GFR estimation based on Cr alone, which can avoid unnecessary expensive diagnostic workup, inappropriate kidney disease diagnosis, incorrect dosing of drugs, and accurately represent the military readiness of patients. Interestingly, in African American patients with recently diagnosed HIV, CKD-EPI using both Cr and CysC without race inclusion led to only a 2.9% overestimation of GFR and was the only equation with no statistically significant bias compared with measured GFR.²⁴

A March 2023 case involving an otherwise healthy 26-year-old male active-duty US Navy member with a history of excessive protein supplement intake and intense exercise < 24 hours before laboratory work was diagnosed with CKD after a measured Cr of 16 mg/dL and an eGFR_Cr of 4 mL/min/1.73 m² without any other evidence of kidney disease. His CysC remained within normal limits, resulting in a normal eGFR_Cys of 121 mL/min/1.73 m², indicating no CKD. His Cr and eGFR recovered 10 days after his clinic visit and cessation of his supplement intake. These findings may not be uncommon given that 65% of active-duty military use protein supplements and 38% use other performance-enhancing supplements, such as creatine, according to a study.²⁵

Unfortunately, the BMP/CMP traditionally used at VA centers use the eGFR_Cr equation, and it is unknown how many primary care practitioners recognize the limitations of these metabolic panels on accurate estimation of kidney function. However, in 2022 an expert panel including VA physicians recommended the immediate use of eGFR_Cr-Cys or eGFR_Cys for confirmatory testing and potentially screening of CKD.²⁶ A small number of VAs have since adopted this recommendation, which should lead to fewer misdiagnoses among US military members as clinicians should now have access to more accurate measurements of GFR.

The VA spends about $18 billion (excluding dialysis) for care for 1.1 to 2.5 million VA patients with CKD.²⁷ The majority of these diagnoses were undoubtedly made using the eGFR_Cr equation, raising the question of how many may be misdiagnosed. Assessment with CysC is currently relatively expensive, but it will likely become more affordable as the use of CysC as a confirmatory test increases.⁵ The cost of a sCr test is about $2.50, while CysC costs about $10.60, with variation from laboratory to laboratory.²⁸ By comparison, a renal ultrasound costs $99 to $140 for uninsured patients.²⁹ Furthermore, the cost of CysC testing is likely to trend downward as more facilities adopt the use of CysC measurements, which can be run on the same analytical equipment currently used for Cr measurements. Currently, most laboratories do not have established assays to use in-house and thus require CysC to be sent out to a laboratory, which increases result time and makes Cr a more attractive option. As more laboratories adopt assays for CysC, the cost of reagents will further decrease.

Given such considerations, confirmation testing of kidney function with CysC in specific patient populations with decreased eGFR_Cr without other features of CKD can offer great medical and financial benefits. A 2023 KDIGO report noted that many individuals may be mistakenly diagnosed with CKD when using eGFR_Cr.³ KDIGO noted that a 2013 meta-analysis of 90,000 individuals found that with a Cr-based eGFR of 45 to 59 mL/min/1.73 m² (42%) had a CysC-based eGFR of ≥ 60 mL/min/1.73 m². An eGFR_Cr of 45 to 59 represents 54% of all patients with CKD, amounting to millions of people (including current and former military personnel).^3,29-31 Correcting a misdiagnosis of CKD would bring significant relief to patients and save millions in health care spending.

Conclusions

In patients who meet CKD criteria using eGFR_Cr but without other features of CKD, we recommend using confirmatory CysC levels and the eGFR_Cr-Cys equation. This will align care with the KDIGO guidelines and could be a cost-effective step toward improving military patient care. Further work in this area should focus on determining the knowledge gaps in primary care practitioners’ understanding of the limits of eGFR_Cr, the potential mitigation of concomitant CysC testing in equivocal CKD cases, and the cost-effectiveness and increased utilization of CysC.

A pair of dueling editorials in the journal Hypertension debate whether our focus should be on sodium or its often neglected partner, potassium.

Should we cut sodium from our diet or eat more potassium to lower blood pressure? The answer requires an intricate understanding of renal physiology that is fascinating. To nephrologists. A meta-analysis of 85 trials showed a consistent and linear. It may also depend on where you live and whether your concern is treating individuals or implementing effective food policy.

The Case for Sodium Restriction

Stephen Juraschek, MD, PhD, of the Beth Israel Deaconess Medical Center, Boston, Massachusetts, co-author of one editorial, told me in a zoom interview that he believes his side of the debate clearly has the stronger argument. Of the two cations in question, there has been infinitely more ink spilled about sodium.

Studies such as INTERSALT, the DASH diet, and TOHP may be the most well-known, but there are many, many intervention studies of sodium restriction’s effect on blood pressure. A meta-analysis of 85 trials of showed a consistent and linear relationship between sodium reduction and blood pressure. In contrast, the evidence base for potassium is more limited and less consistent. There are half as many trials with potassium, and its ability to lower blood pressure may depend on how much sodium is present in the diet.

An outlier in the sodium restriction evidence base is the PURE study, which suggested that extreme sodium restriction could increase cardiovascular mortality, but the trial suffered from two potential issues. First, it used a single spot urine specimen to measure sodium rather than the generally accepted more accurate 24-hour urine collection. A reanalysis of the TOHP study using a spot urine rather than a 24-hour urine collection changed the relationship between sodium intake and mortality and possibly explained the U-shaped association observed in PURE. Second, PURE was an observational cohort and was prone to confounding, or in this case, reverse causation. Why did people who consumed very little salt have an increased risk for cardiovascular disease? It is very possible that people with a high risk for cardiovascular disease were told to consume less salt to begin with. Hence B led to A rather than A leading to B.

The debate on sodium restriction has been bitter at times. Opposing camps formed, and people took sides in the “salt wars.” A group of researchers, termed the Jackson 6, met and decided to end the controversy by running a randomized trial in US prisons (having discounted the options of long-term care homes and military bases). They detailed their plan in an editorial in Hypertension. The study never came to fruition for two reasons: the obvious ethical problems of experimenting on prisoners and the revelation of undisclosed salt industry funding.

More recent studies have mercifully been more conventional. The SSaSS study, a randomized controlled trial of a salt substitute, provided the cardiovascular outcomes data that many were waiting for. And CARDIA-SSBP, a cross-over randomized trial recently presented at the American Heart Association meeting, showed that reducing dietary sodium was on par with medication when it came to lowering blood pressure.

For Dr. Juraschek, the evidence is clear: “If you were going to choose one, I would say the weight of the evidence is still really heavily on the sodium side.”

The Case for Potassium Supplementation

The evidence for salt restriction notwithstanding, Swapnil Hiremath, MD, MPH, from the University of Ottawa, Ontario, Canada, argued in his editorial that potassium supplementation has gotten short shrift. Though he admits the studies for potassium supplementation have been smaller and sometimes rely on observational evidence, the evidence is there. In the distal convoluted tubule, the sodium chloride cotransporter (NCC), aka the potassium switch, is turned on by low potassium levels and leads to sodium reabsorption by the kidney even in settings of high sodium intake (Figure). To nonnephrologists, renal physiology may be a black box. But if you quickly brush up on the mechanism of action of thiazide diuretics, the preceding descriptor will make more sense.

Medscape

Realistic Diets and Taste Issues

“We know that increasing potassium, decreasing sodium is useful. The question is how do we do that?” says Dr. Hiremath. Should we encourage fruit and vegetable consumption in a healthy diet, give potassium supplements, or encourage the use of low-sodium salt substitutes?

Recommending a healthier diet with more fruits and vegetables is a no-brainer. But getting people to do it is hard. In a world where fruit is more expensive than junk food is, economic realities may drive food choice regardless of our best efforts. The 4700 mg of potassium in the DASH eating plan is the equivalent of eleven bananas daily; although not impossible, it would require a substantive shift in eating patterns for most people.

Given that we prescribe iron, vitamin B12, calcium, and vitamin D to patients who need them, why not potassium tablets to help with blood pressure? Granted, there are concerns about inducing hyperkalemia. Also, why not just prescribe a proven anti-hypertensive, such as ramipril, which has the added benefit of helping with renal protection or cardiac remodeling? Dr. Hiremath points out that patients are far less reluctant to take dietary supplements. Medication is something you take when sick. A supplement is seen as “natural” and “healthy” and might be more attractive to people resistant to prescription meds.

Another drawback of oral potassium supplementation is taste. In a Consumer Reports taste test, potassium chloride fared poorly. It was bitter and had a metallic aftertaste. At least one tester wouldn’t ever consume it again. Potassium citrate is slightly more palpable.

Salt substitutes, like the 75:25 ratio of sodium to potassium used in SSaSS, may be as high as you can go for potassium in any low-sodium salt alternative. If you go any higher than that, the taste will just turn people off, suggests Dr. Hiremath.

But SsaSS, which was done in China, may not be relevant to North America. In China, most sodium is added during cooking at home, and the consumption of processed foods is low. For the typical North American, roughly three quarters of the sodium eaten is added to their food by someone else; only about 15% is added during cooking at home or at the dinner table. If you aren’t someone who cooks, buying a salt substitute is probably not going to have much impact.

Given that reality, Dr. Juraschek thinks we need to target the sodium in processed foods. “There’s just so much sodium in so many products,” he says. “When you think about public policy, it’s most expeditious for there to be more regulation about how much is added to our food supply vs trying to get people to consume eight to 12 servings of fruit.”

No Salt War Here

Despite their different editorial takes, Dr. Hiremath and Dr. Juraschek largely agree on the broad strokes of the problem. This isn’t X (or Twitter) after all. Potassium supplementation may be useful in some parts of the world but may not address the underlying problem in countries where processed foods are the source of most dietary sodium.

The CARDIA-SSBP trial showed that a very low–sodium diet had the same blood pressure–lowering effect as a first-line antihypertensive, but most people will not be able to limit themselves to 500 mg of dietary sodium per day. In CARDIA-SSBP, just as in DASH, participants were provided with meals from study kitchens. They were not just told to eat less salt, which would almost certainly have failed.

“We should aim for stuff that is practical and doable rather than aim for stuff that cannot be done,” according to Dr. Hiremath. Whether that should be salt substitutes or policy change may depend on which part of the planet you live on.

One recent positive change may herald the beginning of a policy change, at least in the United States. In March 2023, the US Food and Drug Administration proposed a rule change to allow salt substitutes to be labeled as salt. This would make it easier for food manufacturers to swap out sodium chloride for a low-sodium alternative and reduce the amount of sodium in the US diet without having a large impact on taste and consumer uptake. Both Dr. Hiremath and Dr. Juraschek agree that it may not be enough on its own but that it’s a start.

Christopher Labos is a cardiologist with a degree in epidemiology. He spends most of his time doing things that he doesn’t get paid for, like research, teaching, and podcasting. Occasionally, he finds time to practice cardiology to pay the rent. He realizes that half of his research findings will be disproved in 5 years; he just doesn’t know which half. He is a regular contributor to the Montreal Gazette, CJAD radio, and CTV television in Montreal, and is host of the award-winning podcast The Body of Evidence.

A version of this article appeared on Medscape.com.

A pair of dueling editorials in the journal Hypertension debate whether our focus should be on sodium or its often neglected partner, potassium.

Should we cut sodium from our diet or eat more potassium to lower blood pressure? The answer requires an intricate understanding of renal physiology that is fascinating. To nephrologists. A meta-analysis of 85 trials showed a consistent and linear. It may also depend on where you live and whether your concern is treating individuals or implementing effective food policy.

The Case for Sodium Restriction

Stephen Juraschek, MD, PhD, of the Beth Israel Deaconess Medical Center, Boston, Massachusetts, co-author of one editorial, told me in a zoom interview that he believes his side of the debate clearly has the stronger argument. Of the two cations in question, there has been infinitely more ink spilled about sodium.

Studies such as INTERSALT, the DASH diet, and TOHP may be the most well-known, but there are many, many intervention studies of sodium restriction’s effect on blood pressure. A meta-analysis of 85 trials of showed a consistent and linear relationship between sodium reduction and blood pressure. In contrast, the evidence base for potassium is more limited and less consistent. There are half as many trials with potassium, and its ability to lower blood pressure may depend on how much sodium is present in the diet.

An outlier in the sodium restriction evidence base is the PURE study, which suggested that extreme sodium restriction could increase cardiovascular mortality, but the trial suffered from two potential issues. First, it used a single spot urine specimen to measure sodium rather than the generally accepted more accurate 24-hour urine collection. A reanalysis of the TOHP study using a spot urine rather than a 24-hour urine collection changed the relationship between sodium intake and mortality and possibly explained the U-shaped association observed in PURE. Second, PURE was an observational cohort and was prone to confounding, or in this case, reverse causation. Why did people who consumed very little salt have an increased risk for cardiovascular disease? It is very possible that people with a high risk for cardiovascular disease were told to consume less salt to begin with. Hence B led to A rather than A leading to B.

The debate on sodium restriction has been bitter at times. Opposing camps formed, and people took sides in the “salt wars.” A group of researchers, termed the Jackson 6, met and decided to end the controversy by running a randomized trial in US prisons (having discounted the options of long-term care homes and military bases). They detailed their plan in an editorial in Hypertension. The study never came to fruition for two reasons: the obvious ethical problems of experimenting on prisoners and the revelation of undisclosed salt industry funding.

More recent studies have mercifully been more conventional. The SSaSS study, a randomized controlled trial of a salt substitute, provided the cardiovascular outcomes data that many were waiting for. And CARDIA-SSBP, a cross-over randomized trial recently presented at the American Heart Association meeting, showed that reducing dietary sodium was on par with medication when it came to lowering blood pressure.

For Dr. Juraschek, the evidence is clear: “If you were going to choose one, I would say the weight of the evidence is still really heavily on the sodium side.”

The Case for Potassium Supplementation

The evidence for salt restriction notwithstanding, Swapnil Hiremath, MD, MPH, from the University of Ottawa, Ontario, Canada, argued in his editorial that potassium supplementation has gotten short shrift. Though he admits the studies for potassium supplementation have been smaller and sometimes rely on observational evidence, the evidence is there. In the distal convoluted tubule, the sodium chloride cotransporter (NCC), aka the potassium switch, is turned on by low potassium levels and leads to sodium reabsorption by the kidney even in settings of high sodium intake (Figure). To nonnephrologists, renal physiology may be a black box. But if you quickly brush up on the mechanism of action of thiazide diuretics, the preceding descriptor will make more sense.

Medscape

Realistic Diets and Taste Issues

“We know that increasing potassium, decreasing sodium is useful. The question is how do we do that?” says Dr. Hiremath. Should we encourage fruit and vegetable consumption in a healthy diet, give potassium supplements, or encourage the use of low-sodium salt substitutes?

Recommending a healthier diet with more fruits and vegetables is a no-brainer. But getting people to do it is hard. In a world where fruit is more expensive than junk food is, economic realities may drive food choice regardless of our best efforts. The 4700 mg of potassium in the DASH eating plan is the equivalent of eleven bananas daily; although not impossible, it would require a substantive shift in eating patterns for most people.

Given that we prescribe iron, vitamin B12, calcium, and vitamin D to patients who need them, why not potassium tablets to help with blood pressure? Granted, there are concerns about inducing hyperkalemia. Also, why not just prescribe a proven anti-hypertensive, such as ramipril, which has the added benefit of helping with renal protection or cardiac remodeling? Dr. Hiremath points out that patients are far less reluctant to take dietary supplements. Medication is something you take when sick. A supplement is seen as “natural” and “healthy” and might be more attractive to people resistant to prescription meds.

Another drawback of oral potassium supplementation is taste. In a Consumer Reports taste test, potassium chloride fared poorly. It was bitter and had a metallic aftertaste. At least one tester wouldn’t ever consume it again. Potassium citrate is slightly more palpable.

Salt substitutes, like the 75:25 ratio of sodium to potassium used in SSaSS, may be as high as you can go for potassium in any low-sodium salt alternative. If you go any higher than that, the taste will just turn people off, suggests Dr. Hiremath.

But SsaSS, which was done in China, may not be relevant to North America. In China, most sodium is added during cooking at home, and the consumption of processed foods is low. For the typical North American, roughly three quarters of the sodium eaten is added to their food by someone else; only about 15% is added during cooking at home or at the dinner table. If you aren’t someone who cooks, buying a salt substitute is probably not going to have much impact.

Given that reality, Dr. Juraschek thinks we need to target the sodium in processed foods. “There’s just so much sodium in so many products,” he says. “When you think about public policy, it’s most expeditious for there to be more regulation about how much is added to our food supply vs trying to get people to consume eight to 12 servings of fruit.”

No Salt War Here

Despite their different editorial takes, Dr. Hiremath and Dr. Juraschek largely agree on the broad strokes of the problem. This isn’t X (or Twitter) after all. Potassium supplementation may be useful in some parts of the world but may not address the underlying problem in countries where processed foods are the source of most dietary sodium.

The CARDIA-SSBP trial showed that a very low–sodium diet had the same blood pressure–lowering effect as a first-line antihypertensive, but most people will not be able to limit themselves to 500 mg of dietary sodium per day. In CARDIA-SSBP, just as in DASH, participants were provided with meals from study kitchens. They were not just told to eat less salt, which would almost certainly have failed.

“We should aim for stuff that is practical and doable rather than aim for stuff that cannot be done,” according to Dr. Hiremath. Whether that should be salt substitutes or policy change may depend on which part of the planet you live on.

One recent positive change may herald the beginning of a policy change, at least in the United States. In March 2023, the US Food and Drug Administration proposed a rule change to allow salt substitutes to be labeled as salt. This would make it easier for food manufacturers to swap out sodium chloride for a low-sodium alternative and reduce the amount of sodium in the US diet without having a large impact on taste and consumer uptake. Both Dr. Hiremath and Dr. Juraschek agree that it may not be enough on its own but that it’s a start.

Christopher Labos is a cardiologist with a degree in epidemiology. He spends most of his time doing things that he doesn’t get paid for, like research, teaching, and podcasting. Occasionally, he finds time to practice cardiology to pay the rent. He realizes that half of his research findings will be disproved in 5 years; he just doesn’t know which half. He is a regular contributor to the Montreal Gazette, CJAD radio, and CTV television in Montreal, and is host of the award-winning podcast The Body of Evidence.

A version of this article appeared on Medscape.com.

A pair of dueling editorials in the journal Hypertension debate whether our focus should be on sodium or its often neglected partner, potassium.

Should we cut sodium from our diet or eat more potassium to lower blood pressure? The answer requires an intricate understanding of renal physiology that is fascinating. To nephrologists. A meta-analysis of 85 trials showed a consistent and linear. It may also depend on where you live and whether your concern is treating individuals or implementing effective food policy.

The Case for Sodium Restriction

Stephen Juraschek, MD, PhD, of the Beth Israel Deaconess Medical Center, Boston, Massachusetts, co-author of one editorial, told me in a zoom interview that he believes his side of the debate clearly has the stronger argument. Of the two cations in question, there has been infinitely more ink spilled about sodium.

Studies such as INTERSALT, the DASH diet, and TOHP may be the most well-known, but there are many, many intervention studies of sodium restriction’s effect on blood pressure. A meta-analysis of 85 trials of showed a consistent and linear relationship between sodium reduction and blood pressure. In contrast, the evidence base for potassium is more limited and less consistent. There are half as many trials with potassium, and its ability to lower blood pressure may depend on how much sodium is present in the diet.

An outlier in the sodium restriction evidence base is the PURE study, which suggested that extreme sodium restriction could increase cardiovascular mortality, but the trial suffered from two potential issues. First, it used a single spot urine specimen to measure sodium rather than the generally accepted more accurate 24-hour urine collection. A reanalysis of the TOHP study using a spot urine rather than a 24-hour urine collection changed the relationship between sodium intake and mortality and possibly explained the U-shaped association observed in PURE. Second, PURE was an observational cohort and was prone to confounding, or in this case, reverse causation. Why did people who consumed very little salt have an increased risk for cardiovascular disease? It is very possible that people with a high risk for cardiovascular disease were told to consume less salt to begin with. Hence B led to A rather than A leading to B.

The debate on sodium restriction has been bitter at times. Opposing camps formed, and people took sides in the “salt wars.” A group of researchers, termed the Jackson 6, met and decided to end the controversy by running a randomized trial in US prisons (having discounted the options of long-term care homes and military bases). They detailed their plan in an editorial in Hypertension. The study never came to fruition for two reasons: the obvious ethical problems of experimenting on prisoners and the revelation of undisclosed salt industry funding.

More recent studies have mercifully been more conventional. The SSaSS study, a randomized controlled trial of a salt substitute, provided the cardiovascular outcomes data that many were waiting for. And CARDIA-SSBP, a cross-over randomized trial recently presented at the American Heart Association meeting, showed that reducing dietary sodium was on par with medication when it came to lowering blood pressure.

For Dr. Juraschek, the evidence is clear: “If you were going to choose one, I would say the weight of the evidence is still really heavily on the sodium side.”

The Case for Potassium Supplementation

The evidence for salt restriction notwithstanding, Swapnil Hiremath, MD, MPH, from the University of Ottawa, Ontario, Canada, argued in his editorial that potassium supplementation has gotten short shrift. Though he admits the studies for potassium supplementation have been smaller and sometimes rely on observational evidence, the evidence is there. In the distal convoluted tubule, the sodium chloride cotransporter (NCC), aka the potassium switch, is turned on by low potassium levels and leads to sodium reabsorption by the kidney even in settings of high sodium intake (Figure). To nonnephrologists, renal physiology may be a black box. But if you quickly brush up on the mechanism of action of thiazide diuretics, the preceding descriptor will make more sense.

Medscape

Realistic Diets and Taste Issues

“We know that increasing potassium, decreasing sodium is useful. The question is how do we do that?” says Dr. Hiremath. Should we encourage fruit and vegetable consumption in a healthy diet, give potassium supplements, or encourage the use of low-sodium salt substitutes?

Recommending a healthier diet with more fruits and vegetables is a no-brainer. But getting people to do it is hard. In a world where fruit is more expensive than junk food is, economic realities may drive food choice regardless of our best efforts. The 4700 mg of potassium in the DASH eating plan is the equivalent of eleven bananas daily; although not impossible, it would require a substantive shift in eating patterns for most people.

Given that we prescribe iron, vitamin B12, calcium, and vitamin D to patients who need them, why not potassium tablets to help with blood pressure? Granted, there are concerns about inducing hyperkalemia. Also, why not just prescribe a proven anti-hypertensive, such as ramipril, which has the added benefit of helping with renal protection or cardiac remodeling? Dr. Hiremath points out that patients are far less reluctant to take dietary supplements. Medication is something you take when sick. A supplement is seen as “natural” and “healthy” and might be more attractive to people resistant to prescription meds.

Another drawback of oral potassium supplementation is taste. In a Consumer Reports taste test, potassium chloride fared poorly. It was bitter and had a metallic aftertaste. At least one tester wouldn’t ever consume it again. Potassium citrate is slightly more palpable.

Salt substitutes, like the 75:25 ratio of sodium to potassium used in SSaSS, may be as high as you can go for potassium in any low-sodium salt alternative. If you go any higher than that, the taste will just turn people off, suggests Dr. Hiremath.

But SsaSS, which was done in China, may not be relevant to North America. In China, most sodium is added during cooking at home, and the consumption of processed foods is low. For the typical North American, roughly three quarters of the sodium eaten is added to their food by someone else; only about 15% is added during cooking at home or at the dinner table. If you aren’t someone who cooks, buying a salt substitute is probably not going to have much impact.

Given that reality, Dr. Juraschek thinks we need to target the sodium in processed foods. “There’s just so much sodium in so many products,” he says. “When you think about public policy, it’s most expeditious for there to be more regulation about how much is added to our food supply vs trying to get people to consume eight to 12 servings of fruit.”

No Salt War Here

Despite their different editorial takes, Dr. Hiremath and Dr. Juraschek largely agree on the broad strokes of the problem. This isn’t X (or Twitter) after all. Potassium supplementation may be useful in some parts of the world but may not address the underlying problem in countries where processed foods are the source of most dietary sodium.

The CARDIA-SSBP trial showed that a very low–sodium diet had the same blood pressure–lowering effect as a first-line antihypertensive, but most people will not be able to limit themselves to 500 mg of dietary sodium per day. In CARDIA-SSBP, just as in DASH, participants were provided with meals from study kitchens. They were not just told to eat less salt, which would almost certainly have failed.

“We should aim for stuff that is practical and doable rather than aim for stuff that cannot be done,” according to Dr. Hiremath. Whether that should be salt substitutes or policy change may depend on which part of the planet you live on.

One recent positive change may herald the beginning of a policy change, at least in the United States. In March 2023, the US Food and Drug Administration proposed a rule change to allow salt substitutes to be labeled as salt. This would make it easier for food manufacturers to swap out sodium chloride for a low-sodium alternative and reduce the amount of sodium in the US diet without having a large impact on taste and consumer uptake. Both Dr. Hiremath and Dr. Juraschek agree that it may not be enough on its own but that it’s a start.

Christopher Labos is a cardiologist with a degree in epidemiology. He spends most of his time doing things that he doesn’t get paid for, like research, teaching, and podcasting. Occasionally, he finds time to practice cardiology to pay the rent. He realizes that half of his research findings will be disproved in 5 years; he just doesn’t know which half. He is a regular contributor to the Montreal Gazette, CJAD radio, and CTV television in Montreal, and is host of the award-winning podcast The Body of Evidence.

A version of this article appeared on Medscape.com.