Learn About A Test



Aminoaciduria is an abnormal amount of amino acids in the urine. Amino acids are the building blocks for proteins in the body.This article discusses the test used to look for increased amounts of amino acids in the urine.See also:Amino acids blood testInborn errors of metabolism

Alternative Names

Amino acids - urine; Urine amino acids

How the test is performed

A clean-catch urine sample is needed. This is often done at your doctor's office or health clinic.

How to prepare for the test

No special preparations are necessary. Make sure your doctor knows about all the medicines you or your child are taking or have recently used. If this test is being done on an infant who is breast-feeding, make sure the health care provider knows what medicines the nursing mother is taking.

How the test will feel

The test involves only normal urination.

Why the test is performed

This test is done to measure amino acid levels in the urine. There are many different types of amino acids. It is common for some of each kind to be found in the urine, but increased levels of individual amino acids can be a sign of an inborn error of metabolism.

Normal Values

The specific value is measured in micromoles per deciliter (micromol/dL).Alanine Children: 65 to 190Adults: 160 to 690Alpha-aminoadipic acid Children: 25 to 78Adults: 0 to 165Alpha-amino-N-butyric acid Children: 7 to 25Adults: 0 to 28Arginine Children: 10 to 25Adults: 13 to 64Asparagine Children: 15 to 40Adults: 34 to 100Aspartic acidChildren: 10 to 26Adults: 14 to 89Beta-alanine Children: 0 to 42Adults: 0 to 93Beta-amino-isobutyric acid Children: 25 to 96Adults: 10 to 235Carnosine Children: 34 to 220Adults: 16 to 125Citrulline Children: 0 to 13Adults: 0 to 11Cystine Children: 11 to 53Adults: 28 to 115Glutamic acid Children: 13 to 22Adults: 27 to 105Glutamine Children: 150 to 400Adults: 300 to 1,040Glycine Children: 195 to 855Adults: 750 to 2,400Histidine Children: 46 to 725Adults: 500 to 1,500Hydroxyproline Children: not measuredAdults: not measuredIsoleucine Children: 3 to 15Adults: 4 to 23Leucine Children: 9 to 23Adults: 20 to 77Lysine Children: 19 to 140Adults: 32 to 290Methionine Children: 7 to 20Adults: 5 to 301-methylhistidine Children: 41 to 300Adults: 68 to 8553-methylhistidine Children: 42 to 135Adults: 64 to 320Ornithine Children: 3 to 16Adults: 5 to 70PhenylalanineChildren: 20 to 61Adults: 36 to 90Phosphoserine Children: 16 to 34Adults: 28 to 95Phosphoethanolamine Children: 24 to 66Adults: 17 to 95Proline Children: not measuredAdults: not measuredSerine Children: 93 to 210Adults: 200 to 695Taurine Children: 62 to 970Adults: 267 to 1,290Threonine Children: 25 to 100Adults: 80 to 320Tyrosine Children: 30 to 83Adults: 38 to 145Valine Children: 17 to 37Adults: 19 to 74Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What abnormal results mean

Increased total urine amino acids may be due to:AlkaptonuriaCanavan diseaseCystinosisCystathioninuriaFructose intoleranceGalactosemiaHartnup diseaseHomocystinuriaHyperammonemiaHyperparathyroidismMaple syrup urine diseaseMethylmalonic acidemiaMultiple myelomaOrnithine transcarbamylase deficiencyOsteomalaciaPropionic acidemiaRicketsTyrosinemia type 1Tyrosinemia type 2Viral hepatitisWilson's disease

Special considerations

Failure to have the urine sample promptly evaluated in the laboratory alters the results of the test.This test is ineffective if the baby is under 6 weeks old and has not been fed dietary protein in the last 48 hours.Urine chromatography is necessary to accurately measure increased levels of specific amino acids.Screening infants for increased levels of amino acids can lead to early diagnosis of an inborn error of metabolism. If the condition is promptly treated, complications such as severe intellectual disability may be prevented.

Review Date: 5/12/2011
Reviewed By: Frank A. Greco, M.D., Ph.D., Director, Biophysical Laboratory, The Lahey Clinic, Burlington, MA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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