Hyperammonemia associated with low doses and concentrations of valproic acid in older adults with neurocognitive disorder.

Hyperammonemia is an idiosyncratic adverse effect associated with valproic acid (VPA). We report 2 patients with neurocognitive disorder who were prescribed low doses of VPA for neuropsychiatric symptoms associated with neurocognitive disorder, and they presented with changes in behavior. On workup, both patients had elevated ammonia concentrations. The aims of the case report are to highlight the importance of laboratory testing for ammonia concentrations in patients with altered mental status especially in the setting of VPA therapy irrespective of the dosage and to discuss possible mechanisms associated with VPA-induced hyperammonemia.