Intravenous arginine dramatically improved hyperammonemia in a patient with late-onset ornithine transcarbamylase deficiency.

We describe a 12 year-old male patient with late-onset ornithine transcarbamylase deficiency, in whom infusion of arginine alone dramatically improved intercurrent hyperammonemia. The plasma glutamine level also decreased while the urea nitrogen level increased with arginine infusion, indicating that accumulated nitrogen was metabolized to urea in response to the arginine infusion.