COMT and Hyponatremia: Afterwards, catechol-o-methyltransferase (COMT) breaks down the primary 3,4-dihydroxy MDMA metabolite into 3,4-dihydroxymethamphetamine (HMMA).[19] Genetic polymorphism is also exhibited for COMT, with roughly 25% of Caucasians having low COMT activity.[20] Meanwhile, HMMA itself stimulates vasopressin release, resulting in excessive water retention and hyponatremia.[21,22] Hence, the low COMT activity in our Caucasian patient may have accounted for a reduced vasopressin secretion and lack of hyponatremia.