Valproate monotherapy induced-delirium due to hyperammonemia: A report of three adult cases with different types of presentation.

One of the important adverse effects of valproate is delirium due to hyperammonemia. In this case report series, we are reporting three cases with interesting and different types of clinical presentation on valproate monotherapy. Valproate-induced delirium may be mistaken for psychosis or worsening of mania leading to improper diagnosis and poor management. We found that there was an elevated level of plasma ammonia in our cases during the delirious state and which decreased when valproate was discontinued. In our cases the serum valproate levels, liver function tests, electroencephalogram, and imaging studies were normal, which were deranged in the previous case reports. We are the first to rechallenge valproate in one of the cases, to prove that valproate caused the hyperammonemia. We suggest that plasma ammonia levels should be monitored routinely in all cases of altered mental status and receiving valproate therapy.