Hyperammonemic coma presenting as Hashimoto's encephalopathy

Hyperammonemia is commonly encountered in active liver disease. Evaluation of patients having hyperammonemia with normal liver function is difficult. We present a case referred to us as undiagnosed hyperammonemic coma with normal liver function, who was subsequently diagnosed to have Hashimoto's encephalopathy. In patients with hyperammonemia without hepatic dysfunction, one must search for the presence of hypothyroidism. Hashimoto's encephalopathy though described to be rare in literature, is often underlooked. In patients with undiagnosed coma, one must look for it as it is easy to diagnose and treat.