Annals of neurology
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A patient with carbamyl phosphate synthetase deficiency had four episodes of hyperammonemia, up to 226 microM, associated with valproate (VPA) treatment. These were accompanied by vomiting, lethargy, and coma. ⋯ Thus, VPA caused symptomatic hyperammonemia in a patient with an impairment in urea synthesis and resulted in mildly elevated ammonium levels in epileptic patients. These data suggest that ammonium levels should be monitored in patients receiving VPA who exhibit signs of vomiting or lethargy.