Case 3: Fever, Vomiting, and Altered Mental Status in a 17-year-old Boy

Presentation

A 17-year-old boy with a history of restrictive eating disorder and orthostatic hypotension presents via emergency medical services from an eating disorder facility with 1 week of dizziness and confusion and 1 day of fever. He also reports months of daily first-morning, nonbloody, and nonbilious vomiting.

On presentation to the emergency department he is febrile (temperature, 102.9°F [39.4°C]), tachycardic (heart rate, 112 beats/min), and hypotensive (blood pressure, 91/46 mm Hg) and requires oxygen via nasal cannula. His weight is 114.2 lb (51.8 kg) (3rd percentile), height is 64.6 in (164 cm) (5th percentile), and BMI is 19.3 (15th percentile). General physical examination findings are normal.

Shortly after arrival, the patient develops a brief episode of upper extremity tonic extension, unresponsiveness, and desaturation. He recovers spontaneously without an apparent postictal period. Repeated neurologic examination reveals slowed but appropriate responses to questioning. Cranial nerves, strength, sensation, and reflexes are normal. Upper extremity coordination is normal, but he has right greater than left ataxia with heel-to-shin testing. The patient is unable to stand for gait and Romberg testing due to dizziness.

Laboratory tests before fluid therapy are remarkable for a serum sodium concentration of 149 mEq/L (149 mmol/L) (reference range, 135–145 mEq/L [135–145 mmol/L]), a serum chloride concentration of 118 mEq/L (118 mmol/L) (reference range, 96–108 mEq/L [96–108 mmol/L]), leukocytosis, and normocytic anemia. Urinalysis results are normal, …