Nephrolithiasis occurs in 5%-12% of the population and frequently on Friday afternoons. Eighty percent of them are calcium oxalate, 20% are in the ureter on presentation, and all of the ones we see hurt ... a lot. We may have more of these with the launch of a new weight-loss medication containing topiramate ER. Topiramate is a carbonic anhydrase inhibitor associated with an increased risk for serum metabolic acidosis and kidney stones.
We have become more comfortable conservatively managing uninfected stones even if there is a degree of hydronephrosis. Stones that are less than 5 mm in size have an 85% chance of passing spontaneously, those that are 5-10 mm have a 50% chance, and those larger than 8 mm have a 20% chance. A systematic review demonstrated the efficacy of tamsulosin for facilitating expulsion of distal ureteral stones less than 10 mm in size (19% improvement) (Urol. Int. 2012;89:107-15). Tamsulosin antagonizes the alpha-1 adrenergic receptors that are present throughout the ureter but have a high concentration in the ureter’s distal third.
But sometimes the stones are stubborn. Is there anything else we can do?
Building on the theory that kidney stones in the ureter cause inflammation, investigators in India conducted a clinical trial investigating the safety and efficacy of alpha-1 adrenergic receptor antagonists combined with prednisolone for the expulsion of distal ureter stones (Korean J. Urol. 2013;54:311-5).
A total of 120 adults presenting with distal ureteral stones (below common iliac vessels as assessed by CT) between 5 mm and 10 mm in size were randomized to one of three groups: A) 0.4 mg tamsulosin plus 5 mg prednisolone; B) naftopidil (a selective alpha-1 adrenergic receptor antagonist not available in the United States) plus 5 mg prednisolone; and C) watchful waiting. Prednisolone was continued for a maximum of 1 week, and the alpha-1 adrenergic receptor antagonist was continued for a maximum of 4 weeks. Patients received intramuscular diclofenac as needed for pain.
The stone expulsion rate was 70%, 87.5%, and 32.5% in groups A, B, and C, respectively. Expulsion rates for groups A and B were significantly greater than group C but not significantly different from one another. In group A, the expulsion rate in the first week was 12.5% and 65% in the second week. No patients expelled stones in the third or fourth week. Use of analgesics was significantly lower in groups A and B. No serious adverse events were noted.
This study does not actually inform us if tamsulosin alone is better than tamsulosin plus steroids, but a previous study from 2006 suggests that this is the case (Eur. Urol. 2006;50:339-44). However, that 2006 study used a steroid equivalent dose five times the dose used in the current study. Recall that prednisolone is equivalent to prednisone, and 5 mg is not huge.
So, for patients with no contraindications for steroids, this might be a reasonable option.
Dr. Ebbert is professor of medicine and a primary care clinician at the Mayo Clinic in Rochester, Minn. He reported having no relevant financial conflicts. The opinions expressed are those of the author.