Hypodipsia and hypernatremia in congenital hydrocephalus.

The authors describe a case of hypodipsia and severe hypernatremia most probably secondary to hydrocephalus in a 22-year-old man in the absence of abnormalities of ADH secretion or metabolism. The patient became hypernatremic only in situations when the decreased spontaneous fluid intake was insufficient to replace that lost caused by sweating or vomiting. Adequate hydration returned the sodium value to normal.