[Hyponatremia and hypoglycemia after treatment with chlorpropamide. Case histories with review of the literature on 18 cases of chlorpropamide induced hyponatremia].

A case of chlorpropamide-induced, symptomatic hyponatremia in a diabetic patient is reported. The hyponatremia was associated with loss of appetite, nausea, and vomiting. These symptoms caused reduced food intake which provoked severe hypoglycemia with disturbed consciousness. The hyponatremia developed when the chlorpropamide doses were increased from 400 to 600 mg/day. Withdrawal of chlorpropamide was followed by remission of hyponatremia. Chlorpropamide-induced hyponatremia is a rare complication and is due to an antidiuretic effect of chlorpropamide caused by increased secretion of adiuretin and potentiation of the effect of chlorpropamide caused by increased secretion of adiuretin and potentiation of the effect of adiuretin in the tubuli of the kidney. This case report and the analysis of 18 published cases in the literature show the following characteristics for chlorpropamide-induced hyponatremia: (1) Hyponatremia is a rare complication in the treatment of diabetics with chlorpropamide. The patients typically are female and over sixty. The dosage of chlorpropamide usually was 500 mg daily or even more. (2) Hyponatremia is often unrecognized for a long time because the symptoms are not specific. The characteristic symptoms include loss of appetite, nausea, vomiting, abdominal pain, confusional state and, rarely, convulsions and coma. Recovery occurs spontaneously after withdrawal of the drug. (3) The incidence of this type of hyponatremia is increased in cases of preexisting tendency to water retention such as heart failure and renal failure, and in cases of diuretic therapy. In the light of these findings, the authors believe that chlorpropamide is no longer a drug of choice in the treatment of diabetic women, especially in cases of preexisting tendency to water retention and in diuretic therapy. In such cases, a sulfonylurea without antidiuretic effect is to be preferred.