Outpatient treatment of propionic acidemia-associated hyperammonemia with N-carbamoyl-l-glutamate in an infant

Objective: The aim of this research letter was to describe the use of N-carbamoyl-l-glutamate as first-line treatment of hyperammonemia in a 4-month-old female patient with propionic acidemia (PA).Methods: A 4-month-old female patient weighing 3.9 kg presented with decompensation with PA and initial hyperammonemia of 451 μg/dL. The patient was receiving a protein-restricted diet supplemented with l-carnitine at a dosage of 100 mg/kg/d during 2 consecutive months. Treatment with N-carbamoyl-l-glutamate was administered during 4 days on an outpatient basis at a dosage of 100 mg/kg/d, representing a dosage of 200 mg BID. The patient's hyperammonemia was monitored for 1 week.Results: The patient's ammonia concentration started to decrease on the first day of the initiation of the treatment with N-carbamoyl-l-glutamate, from 451 to 68 μg/dL (normal range, 10-80 μg/dL) at day 6 of follow-up. The patient did not require intravenous fluids, invasive procedures, or hospitalization.Conclusion:N-carbamoyl-l-glutamate, combined with a protein-restricted diet and l-carnitine supplementation, was apparently effective as first-line treatment of hyperammonemia in this infant with PA.