Amino Acid Analysis
Plasma
Performed by: Quest Diagnostics
Amino Acid analysis is necessary for the diagnosis of a variety of inborn errors of metabolism. These include, but are not limited to:
- phenylketonuria
- tyrosinemia
- citrullinemia
- non-ketotic hyperglycinemia
- maple syrup urine disease
- and homocystinuria.
The assay is also key for the continued monitoring of treatment plans for these disorders and useful for assessing nutritional status of patients.
Interpretive Information:
Elevation of 1 or more amino acids may be diagnostic of an aminoacidopathy. Elevated amino acid levels are also associated with noninherited diseases such as severe liver disease and renal tubular disorders (eg, Fanconi syndrome).
Decreased levels of amino acids are associated with malnutrition as seen in the elderly or those with poor protein intake or gastrointestinal disease.
Additional laboratory testing is required to diagnose other inherited disorders (ie, lactic acidosis, organic aciduria, and some urea cycle defects). Results should be evaluated in the context of clinical findings and/or additional test results.
Infant formulas that are supplemented with amino acids (particularly methionine and homocitrulline) and parenteral nutrition may affect the clinical accuracy of this test. Bacterial contamination of specimens and certain medications, such as valproic acid, can also affect the levels of specific amino acids. In addition, the absence of a protein-containing diet in newborns may preclude detection of selected aminoacidopathies.
References:
Part 8. Amino Acids. In: Scriver CR, Beaudet AL, Valle D, Sly WS, Childs B, Kinzler KW, Vogelstein B, eds. The Metabolic and Molecular Bases of Inherited Disease. 8th ed. New York, NY: McGraw-Hill, Inc; 2001;1665-2105.
Part IV. Disorders of amino acid metabolism and transport. Fernandes J, Saudubray J-M, Van den Berghe G, eds. Inborn Metabolic Diseases Diagnosis and Treatment. 3rd ed. New York, NY: Springer; 2000;169-273.
Part 2. Disorders of amino acid metabolism. Nyhan WL, Barshop BA, Ozand PT, eds. Atlas of Metabolic Diseases. 2nd ed. New York, NY: Oxford University Press Inc; 2005;109-189.
Blau N, Duran M, Blaskovics ME, Gibson KM, eds. Physician's Guide to the Laboratory Diagnosis of Metabolic Diseases. 2nd ed. New York, NY: Springer; 2003.
Heiblim DI, Evans HE, Glass L, et al. Child neurology: amino acid concentrations in cerebrospinal fluid. Arch Neurol. 1978;35:765-768.
Goldsmith RF, Earl JW, Cunningham AM. Determination of delta-aminobutyric acid and other amino acids in cerebrospinal fluid of pediatric patients by reversed-phase liquid chromatography. Clin Chem. 1987;33:1736-1740.
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Biomarkers included in this panel:
Alanine is a nonessential amino acid. It is the second most abundant amino acid in circulation, after glutamine. It is found in many foods including eggs, meat, lentils, and fish. Alanine is involved in sugar metabolism for energy and is important in
Learn moreArginine is found in all protein foods and is very abundant in seeds and nuts. It is considered a semi-essential amino acid during early development, infection/inflammation, or renal and/or intestinal impairment.
Learn moreAsparagine is a non-essential protein amino acid that is present in many fruits and vegetables including asparagus, from which it gets its name. Other dietary sources include meat, potatoes, eggs, nuts, and dairy. It can also be formed from aspartic
Learn moreAspartic acid is a nonessential amino acid that plays roles in many important metabolic processes, such as energy production (citric acid cycle), hormone metabolism, CNS activation, and the urea cycle. It is found in many protein sources such as oyst
Learn moreBeta-aminoisobutyric acid (also known as 3-aminoisobutyric acid) is a non-protein amino acid formed by the catabolism of valine and the nucleotide thymine. It is further catabolized to methylmalonic acid semialdehyde and propionyl-CoA. Levels are con
Learn moreCitrulline is an intermediate, nonprotein-forming amino acid in the urea cycle serving as a precursor to arginine. It derives its name from the watermelon (Citrullus vulgaris), where it was first isolated and identified. It is easily absorbed by the
Learn moreCystathionine is an intermediate dipeptide within the process of transsulfuration. Transsulfuration is the main route for irreversible homocysteine disposal, glutathione production, and energy. The initial step involves the enzyme cystathionine &beta
Learn moreGlutamic acid is a nonessential amino acid is derived from the diet and from the breakdown of gut proteins. Glutamate is a major excitatory neurotransmitter in the brain. It plays a role in neuronal differentiation, migration, and survival in the dev
Learn moreGlutamine is a nonessential amino acid and is the most abundant amino acid in the body. It is formed from glutamate using the enzyme glutamine synthetase. Approximately 80% of glutamine is found in the skeletal muscle, and this concentration is 30 ti
Learn moreGlycine is an amino acid with various important functions within your body, including detoxification, DNA formation, the synthesis of hemoglobin, and as a part of brain neurotransmission pathways. Glycine and serine are interchangeable.
Learn moreHistidine is a semi-essential amino acid which is formed in the breakdown of carnosine. Red meat is a common source of carnosine, and therefore histadine. Other food sources include poultry, fish, nuts, seeds, and grains. Histidine and histamine have
Learn moreHydroxyproline is a collagen related amino acid. Hydroxyproline is a nonessential amino acid, which means that it is manufactured from other amino acids in the liver. Hydroxyproline is necessary for the construction of the body’s major structur
Learn moreBranched Chain Amino Acids (Isoleucine, Leucine, Valine) are the three branched chain amino acids (BCAAs). Branched chain amino acids (BCAA) are essential amino acids and must be obtained from the diet (mainly meat, grains, and dairy).
Learn moreBranched Chain Amino Acids (Isoleucine, Leucine, Valine) are the three branched chain amino acids (BCAAs). Branched chain amino acids (BCAA) are essential amino acids and must be obtained from the diet (mainly meat, grains, and dairy).
Learn moreLysine is a nutritionally essential amino acid abundant in meat, fish, fowl, and legumes and is needed for formation of body proteins and enzymes. Lysine can be methylated using S-adenosylmethionine (SAM) to synthesize carnitine, which is needed f
Learn moreMethionine is an essential amino acid that plays an important role in the methylation cycle. Methionine is obtained from dietary intake or through homocysteine remethylation. Methionine’s dietary sources include eggs, fish, meats, Brazil nuts,
Learn moreOrnithine is an intermediate nonprotein-forming amino acid of the urea cycle. Arginine is converted to ornithine via the arginase enzyme, with urea as a byproduct. Ornithine combined with carbamoyl phosphate is then converted into citrulline via the
Learn morePhenylalanine is an essential amino acid found in most foods which contain protein such as meat, fish, lentils, vegetables, and dairy. Phenylalanine is the precursor to another amino acid, tyrosine. Because tyrosine is needed to form several neurotra
Learn moreProline is a nonessential amino acid. It contains a secondary α-imino group and is sometimes called an α-imino acid. Proline, and its metabolite hydroxyproline, constitute a third of the total amino acids found in collagen. Lysine, prolin
Learn moreSerine is a nonessential amino acid used in protein biosynthesis and can be derived from four possible sources: dietary intake, degradation of protein and phospholipids, biosynthesis from glycolysis intermediate 3-phosphoglycerate, or from glycine.
Learn moreTaurine differs from other amino acids because a sulfur group replaces the carboxyl group of what would be the nonessential amino acid, β-alanine. It takes part in biochemical reactions and is not fully incorporated into proteins. In most tissue
Learn moreThreonine is a large neutral amino acid and a precursor for the amino acid glycine. Foods that contain relatively high amounts of threonine include cheeses (especially Swiss), meat, fish, poultry, seeds, walnuts, cashews, almonds and peanuts. Threoni
Learn moreTryptophan is involved in serotonin production via vitamin B6-dependent pathways resulting in the intermediate 5-hydroxytryptophan (5-HTP). 5-HTP is often used as a supplement for serotonin formation instead of tryptophan, which can be quickly met
Learn moreTyrosine is a conditionally essential amino acid which can come directly from the digestion of dietary protein. Common food sources include dairy, beans, whole grains, meat, and nuts. If intake is insufficient, tyrosine can be formed from the essenti
Learn moreBranched Chain Amino Acids (Isoleucine, Leucine, Valine) Isoleucine, leucine and valine are the three branched chain amino acids (BCAAs). Branched chain amino acids (BCAA) are essential amino acids and must be obtained from the diet (mainly meat, gra
Learn more