[Inappropriate ADH secretion caused by alcohol withdrawal: a rare cause of hyponatremia].

A 52-year-old man, known to be alcohol dependent, was admitted to hospital because of intense drowsiness. He had previously drunk over 100 g alcohol daily, but for the last 2 days "not a drop". Serum sodium concentration was 103 mmol/l, serum osmolarity was low (216 mosmol/l) and urine osmolarity remarkably high (373 mosmol/l). These abnormalities, taken in conjunction with his normal water balance (absence of obvious edema or dehydration), suggested the diagnosis of inappropriate secretion of antidiuretic hormone (ADH), and this was confirmed by a water loading test. Exclusion of the recognized causes of inappropriate ADH secretion left alcohol withdrawal as the only tenable explanation. The reabsorption of water which it induced was the cause of the patient's hyponatraemia and drowsiness. Restriction of fluid intake to 500 ml daily with continued total abstinence from alcohol led to rapid recovery. The discovery of hyponatraemia in an alcoholic in a state of normal water balance should rouse suspicion of inappropriate ADH secretion.