Arginine

Arginine is an amino acid important for protein synthesis, immune function, and blood vessel health. This test measures arginine on a dried blood spot (from a heel prick), commonly used in newborn screening. Elevated blood arginine levels can indicate several inherited metabolic disorders, including argininemia (argininase deficiency) and other urea cycle disorders. These rare genetic conditions cause intellectual disability, seizures, and progressive neurological problems if untreated. Early detection through newborn screening allows for dietary management and medical treatment to prevent serious complications. This test may also be ordered in older individuals with neurological symptoms or family history of metabolic disease.