Cases That Test Your Skills

Persistent altered mental status

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Mr. O, age 24, presents to the ED weak, sluggish, and incoherent. He has a history of schizophrenia and poor medication adherence. What could be causing his persistent altered mental status?



CASE Sluggish, weak, and incoherent

Mr. O, age 24, who has a history of schizophrenia and obesity, presents to the emergency department (ED) for altered mental status (AMS). His mother reports that he has been sluggish, weak, incoherent, had no appetite, and that on the day before admission, he was drinking excessive amounts of water and urinating every 10 minutes.

HISTORY Multiple ineffective antipsychotics

Mr. O was diagnosed with schizophrenia at age 21 and struggled with medication adherence, which resulted in multiple hospitalizations for stabilization. Trials of haloperidol, risperidone, paliperidone palmitate, and valproic acid had been ineffective. At the time of admission, his psychotropic medication regimen is fluphenazine decanoate, 25 mg injection every 2 weeks; clozapine, 50 mg/d; lithium carbonate, 300 mg twice a day; benztropine, 2 mg every night; and trazodone, 50 mg every night.

EVALUATION Fever, tachycardia, and diabetic ketoacidosis

Upon arrival to the ED, Mr. O is obtunded, unable to follow commands, and does not respond to painful stimuli. On physical exam, he has a fever of 38.4°C (reference range 35.1°C to 37.9°C); tachycardia with a heart rate of 142 beats per minute (bpm) (reference range 60 to 100); tachypnea with a respiratory rate of 35 breaths per minute (reference range 12 to 20); a blood pressure of 116/76 mmHg (reference range 90/60 to 130/80); and hypoxemia with an oxygen saturation of 90% on room air (reference range 94% to 100%).

Mr. O is admitted to the hospital and his laboratory workup indicates diabetic ketoacidosis (DKA), with a glucose of 1,700 mg/dL; anion gap of 30 (reference range 4 to 12 mmol/L); pH 7.04 (reference range 7.32 to 7.42); serum bicarbonate 6 (reference range 20 to 24 mEq/L); beta-hydroxybutyrate 11.04 (reference range 0 to 0.27 mmol/L); urine ketones, serum osmolality 407 (reference range 280 to 300 mOsm/kg); and an elevated white blood cell count of 18.4 (reference range 4.5 to 11.0 × 109/L). A CT scan of the head is negative for acute pathology.

Initially, all psychotropic medications are held. On Day 3 of hospitalization, psychiatry is consulted and clozapine, 50 mg/d; lithium, 300 mg/d; and benztropine, 1 mg at night, are restarted; however, fluphenazine decanoate and trazodone are held. The team recommends IV haloperidol, 2 mg as needed for agitation; however, it is never administered.

Imaging rules out deep vein thrombosis, cardiac dysfunction, and stroke, but a CT chest scan is notable for bilateral lung infiltrates, which suggests aspiration pneumonia.

Mr. O is diagnosed with diabetes, complicated by DKA, and is treated in the intensive care unit (ICU). Despite resolution of the DKA, he remains altered with fever and tachycardia.

Continue to: On Day 6 of hospitalization...


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