title: Determination of Phenylalanine and Tyrosine by High Performance Liquid Chromatography-Tandem Mass Spectrometry.
abstract: Hyperphenylalaninemia/phenylketonuria (PKU) is one of the most common inborn errors of amino acid metabolism affecting about 1:15,000 infants in the United States. PKU is an autosomal recessive disorder that if untreated results in mental retardation. The most common cause of PKU is deficiency of the enzyme phenylalanine hydroxylase that converts phenylalanine to tyrosine. Tyrosine deficiency results in impaired synthesis of catecholamines and thyroxine. Less commonly, it can result from defects in the synthesis or regeneration of tetrahydrobiopterin (BH4), an essential cofactor for the enzyme phenylalanine hydroxylase. Increased phenylalanine and decreased tyrosine in blood are used in the diagnosis and follow-up of patients with PKU. LC/MS/MS method is described for the quantification of phenylalanine and tyrosine.
authors.affiliation: Department of Pathology and Laboratory Medicine, Children's Mercy Hospitals and Clinics, 2401 Gillham Road, Kansas City, MO, 64108, USA.
authors.forename: Judy
authors.initials: J
authors.lastname: Peat
authors.affiliation: Department of Pathology and Laboratory Medicine, Children's Mercy Hospitals and Clinics, 2401 Gillham Road, Kansas City, MO, 64108, USA. ugarg@cmh.edu.|University of Missouri School of Medicine, Kansas City, MO, USA. ugarg@cmh.edu.
authors.forename: Uttam
authors.initials: U
authors.lastname: Garg
mesh_terms: D001774:Blood Chemical Analysis / Q000295:instrumentation / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D010649:Phenylalanine / Q000097:blood*; D013223:Statistics as Topic; D053719:Tandem Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D014443:Tyrosine / Q000097:blood*
chemical_list: D014443:Tyrosine; D010649:Phenylalanine
keywords: Hyperphenylalaninemia; PKU; Phenylalanine; Phenylalanine hydroxylase; Phenylketonuria; Tandem mass spectrometry; Tetrahydrobiopterin; Tyrosine