Sodium valproate induced hyperammonaemia in an elderly patient with affective disorder

A 60 year old patient with bipolar affective disorder presented with clinical features suggestive of encephalopathy two weeks after commencing treatment with sodium valproate. He developed sudden onset alteration of sleep pattern, extreme agitation and hallucinations. He was disoriented in time, place, and person. Serum valproate level was within the therapeutic range. SGOT, SGPT, serum creatinine and echocardiogram were normal. Serum ammonia level which was 90 μg/dl (range: 25 - 80 μg/dl) at the time of admission had risen to 180 μg /dl on the 3rd day of hospital stay. Rapid clinical recovery from encephalopathy resulted a few days after withholding sodium valproate.