Orotic Acid, Quantitative (Urine)
This test is used in the evaluation of patients with hyperammonemia and a suspected urea cycle defect, and is typically ordered in conjunction with plasma amino acids and urine organic acids.
Orotic acid levels are elevated in the urea cycle defects ornithine transcarbamylase (OTC) deficiency, citrullinemia and argininosuccinic acidemia, as well as the mitochondrial transport disorder hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome. Orotic acid is also elevated in hereditary orotic aciduria, or uridine monophosphate synthase deficiency, an autosomal recessive disorder characterized by megaloblastic anemia and crystalluria.
