Hypothyroidism may exacerbate valproate-related hyperammonemic delirium.

Although it is well known that valproic acid (VPA) can induce hyperammonemia [1], few reports have been concerned with its relationship to hypothyroidism. Here we present a bipolar disorder patient with hypothyroidism (in fact, merely subclinical hypothyroidism) who experienced hyperammonemic delirium during VPA treatment.