Polyuria and Inappropriate Secretion of Arginine Vasopressin in Hypothalamic Sarcoidosis

Inappropriate arginine vasopressin release and polyuria with excessive thirst were found in a patient with hypothalamic sarcoidosis subsequently confirmed at autopsy. He became intensely thirsty during a 5% saline infusion at a plasma osmolality of 274 mosmol/liter. The normal thirst threshold under these conditions is 294 ± 3 mosmol/liter (±SD). An increase in radioimmunoassayable arginine vasopressin ws detected at an inappropriately low plasma osmolality, and free water clearance was negative despite a plasma osmolality of 265 ± 5 mosmol/liter with ad libitum fluid intake. The syndrome of inappropriate antidiuresis has not been described previously in combination with hypothalamic sarcoidosis. Demeclocycline therapy was associated with an exacerbation of the patient's polyuria. Propranolol administration, however, was associated with a reduction of urine output and an increase in plasma osmolality to 279 mosmol/liter on one and 299 mosmol/liter on another occasion.