Risperidone and hyponatremia: a case report.

A 48 year-old white male not suffering from endocrine disease or polydipsia, not taking diuretics, and suffering from no renal disease was started on risperidone and discharged on no other drug from Western Missiouri Mental Health Center (WMMHC) after an 8-day hospitalization. Seven days later he was admitted to a university medical center with generalized seizures, hyponatremia, respiratory failure, and rhabdomyalysis. He eventually recovered, was transferred back to WMMHC, and stabilized on appropriate medication. A search of the literature indicates no case reports linking risperidone to hyponatremia. It is assumed that the mechanism of hyponatremia is similar to other psychotropic medication in that it is secondary to the syndrome of inappropriate antidiuretic hormone (SIADH).