- To determine whether brief (3 day) treatment with N-carbamylglutamate can improve ureagenesis in adult healthy controls and patients with the following inborn errors of metabolism: N-acetylglutamate synthetase deficiency, propionic acidemia, methylmalonic acidemia, carbamylphosphate synthase deficiency, ornithine transcarbamylase deficiency and the syndrome of hyperammonemia, hypoglycemia and hyperinsulinemia (HHH Syndrome).