N-carbamylglutamate in emergency management of hyperammonemia in neonatal acute onset propionic and methylmalonic aciduria.

In propionic aciduria and methylmalonic aciduria, hyperammonemia as a symptom of metabolic decompensation is one of the major clinical problems. Hyperammonemia is a true neonatal emergency with high mortality and neurological complications in most survivors. It requires a rapid and vigorous treatment in order to normalize the ammonia concentration as fast as possible. We report on two full-term neonates, one with propionic aciduria and the other with methylmalonic aciduria, whose plasma ammonia concentrations responded dramatically to oral N-carbamylglutamate. N-carbamylglutamate, added to the classic treatment, quickly normalized plasma ammonia levels in both patients and avoided the need of hemodialysis or peritoneal dialysis. A particularly sudden fall of ammonia was obtained in one patient through beginning N-carbamylglutamate treatment precociously.