Unusual cause of hyperammonemia in two cases with short-term and long-term valproate therapy successfully treated by single dose carglumic acid
A 17-months-old male has a history of mental and motor retardation, microcephaly, and epilepsy. He was admitted to the intensive care unit with seizure and respiratory depression. Supportive care in the form of mechanical ventilation, hydration, and antibiotics were administered. His medications included valproate (50 mg/kg/day po) and phenobarbital (5 mg/kg/day) for the last 1 year. An electroencephalography revealed hypsarrhythmia. Magnetic resonance imaging showed schizencephaly. He was consulted to department of pediatric metabolism due to diagnostic confusion with nonketotic hyperglycinemia. His metabolic tests were normal including tandem mass spectrometry and urine organic acid analysis. His serum ammonia level was 189 μg/dl. His liver function test results including aspartate aminotransferase and alanine aminotransferase were within normal limits. After discontinuation of VPA and initiation of carglumic acid 100 mg/kg by nasogastric route, his serum ammonia concentration decreased to 69 μg/dl within 12 h. His neurologic status improved within a day.