A 76-year-old male with end-stage renal disease status post deceased-donor kidney transplant, gastric bypass, bradycardia, atrial fibrillation, hypertension, obstructive sleep apnea, and osteoporosis secondary to hyperparathyroidism presented with decreased oral intake, generalized weakness, and malaise. On arrival, he was encephalopathic and found to be hypothermic (89°F), hypoglycemic (undetectable), bradycardic (idioventricular rhythm at 30 bpm), hyperkalemic (5.9 mmol/L), and in oliguric renal failure. He was admitted to the MICU for management.
The patient had two prior admissions within the past six months for similar episodes of hypothermia with inconclusive workups. Correction of metabolic and electrolyte abnormalities led to marked improvement in his encephalopathy, but he continued to have recurrent hypothermia without clear etiology. Differential diagnoses included hypothyroidism, adrenal insufficiency, malnutrition, hypoglycemia, central nervous system pathology, and sepsis. Laboratory testing revealed normal thyroid function, normal morning cortisol level, normal ACTH stimulation test, and negative infectious workup. Copper and zinc levels were low and subsequently repleted. Nutritional evaluation revealed no evidence of malnutrition.
Hypoglycemia was attributed to impaired renal clearance and possible dumping syndrome, supported by postprandial diarrhea and history of gastric bypass. Dietary modifications improved glycemic control. MRI of the brain (motion-degraded) showed no acute infarct, hemorrhage, mass, or structural abnormality. Despite extensive evaluation, no definitive etiology for the recurrent hypothermia was identified. Shapiro syndrome was therefore considered, and melatonin supplementation was discontinued.
No further episodes of hypothermia occurred during the final 48 hours of hospitalization following patient optimization.