Abuse of 3,4-Methylenedioxymethamphetamine (MDMA, commonly called ecstasy) has been associated with acute symptomatic hyponatraemia with the syndrome of inappropriate antidiuretic-hormone secretion (SIADH). In one case, raised antidiuretic-hormone (arginine vasopressin; AVP) concentration was found. We investigated whether the hyponatraemic effect of MDMA is a direct effect of AVP secretion.
