Syndrome of inappropriate antidiuretic hormone secretion. A complication of high-dose intravenous melphalan.

Melphalan is now being investigated as an intravenous (IV) bolus chemotherapeutic agent in children with resistant tumors involving the bone marrow. Two patients received 2 mg/kg melphalan, IV bolus; 10 patients received 1 mg/kg. Seven of the ten patients receiving 1 mg/kg had noticeable downward trends in the serum sodium concentrations, whereas both patients receiving 2 mg/kg developed hyponatremia (serum sodium concentration [SNa], mEq/l = 124-125) and inappropriate urinary sodium losses. Syndrome of inappropriate antidiuretic hormone (SiADH) is a previously unreported complication of high dose bolus melphalan therapy.