Water intoxication in a patient with the Prader-Willi syndrome treated with desmopressin for nocturnal enuresis

Purpose: We report on a girl with the Prader-Willi syndrome who received desmopressin for nocturnal enuresis, and water intoxication developed after she ingested a large amount of fluid. Materials and Methods: The patient received 10 mg. desmopressin at bedtime for enuresis. She was hospitalized when a major motor seizure and coma (Glasgow coma scale 8) occurred after ingesting 48 ounces of fluid. Treatment included 3% saline, followed by 5% dextrose in water and sodium chloride given intravenously. Results: Serum sodium increased to 128 mEq./l. and serum glucose remained normal. Computerized tomography and magnetic resonance imaging of the head were normal and revealed no evidence of cerebral pontine myelinosis. Patient consciousness returned to normal by day 5 after the seizure. Conclusions: In patients treated with desmopressin the risk of a seizure or altered level of consciousness can be minimized by not ingesting large quantities of fluid. We recommend that patients drink no more than 8 ounces of fluid on any evening that desmopressin is administered.