[Severe hyponatremia associated with captopril therapy in dilated cardiomyopathy: a case report]

A 47-year-old man, with dilated cardiomyopathy developed severe hyponatremia and hypoosmolarity during captopril therapy. He also had an inappropriate elevation of antidiuretic hormone and urine osmolarity, but no evidence of dehydration, renal or suprarenal disturbances. The hyponatremia and hypoosmolarity improved after withdrawal of captopril alone, and recurred after readministration of captopril. We conclude that the hyponatremia may be caused by high secretion of prostagrandin and bradykinin associated with captopril therapy.