Use

Diagnosis and monitoring of inherited aminoacidurias, organic acidurias, and urea cycle defects. May be used as a follow-up confirmatory test to some abnormal newborn screen results. In most, but not all, cases where an amino acid is elevated in blood, it will also be elevated in urine. Some disorders, primarily those involving defective renal transport, will only manifest elevated amino acids in urine. In general, urinary amino acid levels are more variable than plasma levels. For this reason, screening for aminoacidopathies in urine alone is discouraged unless a disorder is suspected that predominantly manifests abnormalities in urine (eg, cystinuria, renal Fanconi syndrome).