Abnormal water retention and symptomatic hyponatraemia in idiopathic diabetes insipidus during chlorpropamide therapy * GIULIO

THE ability of chlorpropamide to reduce urinary volume in patients with neurogenic diabetes insipidus has been recently described by Arduino, Ferraz & Rodriguez (1966), Meinders, Touber & De Vries (1967), Reforzo-Membrives et al. (1968), Hocken & Longson (1968), and Andreani, Cinotti & Stirati (1969). This therapy is potentially of great importance in the treatment of neurogenic diabetes insipidus; therapy with chlorpropamide, however, is not always without complications both in the short or longterm management of these patients. Initially there were no reports that patients with diabetes insipidus undergoing therapy with chlorpropamide were prone to hypoglycaemic episodes (Meinders, Touber & De Vries, 1967; ReforzoMembrives et al., 1968), but with increasing use of this type of therapy it soon became apparent that hypoglycaemia was the most frequent and important complication. We have observed symptomatic hypoglycaemia in the early phases of treatment, but with continued treatment it becomes less frequent (Cinotti et al., 1969). In this paper we emphasize that these patients, when treated with chlorpropamide, may be also subject to water retention and may present the clinical symptoms of water intoxication. Observations on a patient with idiopathic neurogenic diabetes insipidus (INDI) who developed water retention and mild symptomatic hyponatraemia during long-term treatment with chlorpropamide are reported. This case may also raise some intriguing questions concerning the mechanism of action of chlorpropamide and the physiopathology of diabetes insipidus. Methods