Hyperammonemia and coma without hepatic dysfunction induced by valproate therapy

The authors report a case of a 41-year-old mentally disabled man with bipol ar disorder who presented to the emergency department with altered mental s tatus. He was found to have a significantly elevated ammonia level (377 muM /L) with no signs of hepatic insufficiency. His coma and hyperammonemia wer e attributed to his chronic valproate therapy. This patient had the highest serum ammonia level ever reported with a therapeutic valproate level in th e absence of any other anticonvulsant therapy, metabolic abnormality, or he patic dysfunction. The authors discuss this case and review the current lit erature on hyperammonemia in valproic acid therapy and the use of L-carniti ne in these patients.