[The combination of ACE inhibitor and thiazide may cause severe hyponatremia]

A case of a woman aged 79 years presenting severe hyponatraemia is described. The patient was not dehydrated and the urine was hypertonic. There was no history of renal, hepatic or cardiac disorders. Some weeks previously she had been treated with lisinopril and bendroflumethiazide on account of arterial hypertension. After withdrawal of the drugs and intensive therapy the patient recovered rapidly. The combination of an ACE-inhibitor and a thiazide drug may lead to serious disturbances in body fluid compartments and serum electrolytes. The need for frequent control of serum electrolytes is emphasized.