Abstract
We report a case of neonatal hyperammonemia resulting from urea cycle disorder. A 5-day-old neonate with complaints of poor feeding and apnea was intubated to relieve dyspnea and was then brought to our hospital. On arrival, she was lethargic and had a seizure. Blood examination revealed a plasma ammonia concentration of 1,175 μg/dl. She was immediately treated by blood purification (continuous hemodialysis, continuous hemofiltration,continuous hemodiafiltration). By the next day, the plasma ammonia concentration decreased by 50%. To achieve a further decrease in the plasma ammonia concentration, we simultaneously administered arginine (500 mg/kg/day) and sodium benzoate (0.7 g/day). After blood purification for 6 days, the plasma ammonia concentration reached ≤200 μg/dl. Once this concentration was achieved, we discontinued blood purification. Two days later, she showed signs of rebound and hepatic failure with increased bilirubin level. Therefore, plasma exchange was performed 4 times, and blood purification was resumed. Blood purification was performed for a week, after which the plasma ammonia concentration was restored. Ammonia is a strong neurotoxic metabolite. Hyperammonemia often results in irreversible central nervous system damage. Its clinical symptoms directly correspond to plasma ammonia levels. Thus, blood purification should be performed at the earliest in cases of neonatal hyperammonemia.
