817 PREVENTION OF NEONATAL HYPERAMMONEMIA IN CITRULLINEMIA

Abstract

Citrullinemia, a rare urea cycle enzymopathy (UCE) due to the absence of argininosuccinate synthetase, is characterized by fulminant hyperammonemia and its associated complications. Recent studies have demonstrated alternative means of waste-nitrogen disposal utilizing both urea cycle intermediates and non-urea cycle Pharmaceuticals in patients with UCE. Poor neurologic outcome has also been shown to occur with prolonged neonatal hyperammonemia coma. Prevention of hyperammonemia is therefore, a primary goal in the initial treatment.We treated a 3.72 kg term male infant whose citrullinemia had been diagnosed by maternal amniocentesis because of a previously affected sibling who had died at 9 days of age. For this infant we instituted immediate neonatal therapy using 4 mM/kg/d of arginine hydrochloride as a continuous intravenous infusion, begun at two hours of age. Postnatal amino acid concentrations remained between 24 and 91 μMol/L even with protein intake as high as 2.0 g/kg/d. The patient remained neurologically asymptomatic and was successfully switched to oral arginine and ornithine and sodium benzoate therapy at one week of age. He was discharged at 14 days of age on the same medications and a diet consisting of commercial formula to provide 1.8 g/kg/d of protein, with additional caloric supplementation by a protein-free formula.Though the long-term prognosis for this infant is unknown, avoidance of catastrophic neonatal hyperammonemia in citrullinemia appears achievable.