1012 TRANSIENT HYPERAMMONEMIA IN TERM AND PRETERM INFANTS

We observed within 6 months 4 infants with severe hyperammonemia, only one of whom has a proven enzyme defect. Of the remaining 3, all appeared normal at birth with Apgars >8. All had blood NH3 >2000 μg/dl, severe neurologic impairment, seizures, and complete apnea. All were treated vigorously with peritoneal dialysis, protein restriction, and high glucose infusion. Case 1 was a 3110 gm male who required ventilatory assistance at age 4 h for respiratory distress. Initial NH3 was 3000 μg/dl at age 30 h. The patient died of respiratory distress at age 8 d with a falling blood NH3. Biochemical studies revealed no evidence of urea cycle defect or organic acid disorder. Case 2 was a 2950 gm female who fed poorly, had irregular breathing, and was found to have a blood NH3 of 2700 μg/dl at age 44 h. Blood NH3 was normal by age 6 d; she tolerated normal protein intake and appears developmentally normal at age 4 m. Case 3 was a 2100 gm female product of a 35 wk gestation. Ventilatory assistance for respiratory distress was needed at age 10 h and initial NH3 was 3000 μg/dl at age 30 h. Blood NH3 was normal by age 7 d. No inborn error was diagnosed, but the patient has not been challenged yet with normal protein intake. Case 2 and probably Case 1 represent severe transient hyperammonemia in term infants. Cases 1 and 3 were similar with early development of respiratory distress and ↑NH3 prior to feeding. We believe neonatal hyperammonemia is more common than is generally recognized.