Hyperammonemia Due to Valproic Acid in the Psychiatric Setting

Abstract

In 1980 Coulter and Allen (1) reported the first case of hyperammonemia, to our knowledge, with otherwise normal hepatic function tests in a child with epilepsy treated with valproic acid. Since that time, there have been several additional case reports and studies within the neurology literature that have established hyperammonemia with otherwise normal hepatic function as a potential side effect of valproic acid, especially in children and adolescents (2). Settle (3) published the first case of hyperammonemia, to our knowledge, in a psychiatric setting in 1995. Several additional cases have followed it. Unfortunately, to date, to our knowledge, there has only been one prospective study published within the psychiatric literature (4). We present here a patient’s history that illustrates how the symptoms of a psychiatric disorder might make the diagnosis of hyperammonemic encephalopathy difficult.