Hypervitaminosis D causing nephrogenic diabetes insipidus in a 5-month-old infant.

Vitamin D intoxication in infancy leads to acute hypercalcemia and subsequent hypercalcuria with nephrocalcinosis. Strategies used for patients with vitamin D intoxication are unsatisfactory and associated with prolonged periods of hypercalcemia. We present a 5-month-old infant who had failure to thrive, refusal to feed, delayed motor development, truncal hypotonia, and dehydration. She had high plasma sodium and osmolality with low urine osmolality, and did not respond to intravenous desmopressin administration. She was diagnosed as nephrogenic diabetes insipidus due to hypercalcemia caused by hypervitaminosis D, and was treated with hydrochlorothiazide 2 mg/kg twice daily, and hydration.