Chlorpropamide-induced hyponatremia.

A 29-year-old woman with severe idiopathic diabetes insipidus, while being treated by a combination of chlorpropamide and chlorothiazide, developed the syndrome of inappropriate secretion of ADH (SIADH) following an overdose of chlorpropamide. The syndrome resolved as the serum chlorpropamide level fell. This report demonstrates that a chlorpropamide-induced SIADH can occur in a patient with idiopathic diabetes insipidus, and it appears that the antidiuretic effect of the drug is dose-related.