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Test ID: AAPD    
Amino Acids, Quantitative, Random, Urine

Useful For Suggests clinical disorders or settings where the test may be helpful

Evaluating patients with possible inborn errors of metabolism

 

May aid in evaluation of endocrine disorders, liver diseases, muscle diseases, neoplastic diseases, neurological disorders, nutritional disturbances, renal failure, and burns

Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.

Includes quantitation of the following amino acids: phosphoserine, phosphoethanolamine, taurine, threonine, serine, asparagine, hydroxyproline, glutamic acid, glutamine, aspartic acid, ethanolamine, sarcosine, proline, glycine, alanine, citrulline, alpha-aminoadipic acid, alpha-amino-n-butyric acid, valine, cystine, cystathionine, methionine, isoleucine, leucine, tyrosine, phenylalanine, beta-alanine, beta-aminoisobutyric acid, ornithine, lysine, 1-methylhistidine, histidine, 3-methylhistidine, carnosine, anserine, argininosuccinic acid, allo-isoleucine, homocitrulline, gamma-amino-n-butyric acid, hydroxylysine, tryptophan, and arginine.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Amino acids are the basic structural units that comprise proteins and are found throughout the body. Many inborn errors of amino acid metabolism, that affect amino acid transport and/or metabolism have been identified, such as phenylketonuria and tyrosinemia. Amino acid disorders can manifest at any age, but most become evident in infancy or early childhood. These disorders result in the accumulation or the deficiency of 1 or more amino acids in biological fluids, which leads to the clinical signs and symptoms of the particular amino acid disorder.

 

The clinical presentation is dependent upon the specific amino acid disorder. In general, affected patients may experience failure to thrive, neurologic symptoms, digestive problems, dermatologic findings, and physical and cognitive delays. If not diagnosed and treated promptly, amino acid disorders can result in mental retardation and death.

 

In addition, amino acid analysis may have clinical importance in the evaluation of several acquired conditions including endocrine disorders, liver diseases, muscle diseases, neoplastic diseases, neurological disorders, nutritional disturbances, renal failure, and burns. General elevations in urine amino acid levels, called aminoaciduria, can be seen in disorders with amino acid transport defects such as lysinuric protein intolerance and Hartnup disease, as well as in conditions with renal tubular dysfunction including Lowe syndrome and Dent disease.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Interpretation Provides information to assist in interpretation of the test results

When abnormal results are detected, a detailed interpretation is given, including an overview of the results and of their significance, a correlation to available clinical information, elements of differential diagnosis, recommendations for additional biochemical testing and in vitro confirmatory studies (enzyme assay, molecular analysis), name and phone number of key contacts who may provide these studies at Mayo or elsewhere, and a phone number to reach one of the laboratory directors in case the referring physician has additional questions.

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Amino acids. In The Metabolic and Molecular Bases of Inherited Disease. Eighth edition. Edited by CR Scriver, AL Beaudet, WS Sly, et al. New York, McGraw-Hill, 2001, pp 1667-2105

2. Camargo SMR, Bockenhauer D, Kleta R: Aminoacidurias: Clinical and molecular aspects. Kidney Int 2008;73:918-925


Urine Amino Acid Reference Values (nmol/mg creatinine)

Age Groups

< or =12 Months

13-35 Months

3-6 Years

7-8 Years

9-17 Years

> or =18 Years

(n=515)

(n=210)

(n=197)

(n=74)

(n=214)

(n=835)

Phosphoserine

PSer

 <1

 <1

 <1

 <1

 <1

 <1

Phosphoethanolamine

PEtN

15-341

33-342

19-164

12-118

<88

<48

Taurine

Tau

37-8300

64-3255

76-3519

50-2051

57-2235

24 -1531

Asparagine

Asn

25-1000

62-884

28-412

38-396

22-283

25-238

Serine

Ser

18-4483

284 -1959

179-1285

153-765

105-846

97-540

Hydroxyproline

Hyp

<2536

<89

<46

<19

<22

 <15

Glycine

Gly

362-18614

627-6914

412-5705

449-4492

316-4249

229-2989

Glutamine

Gln

139-2985

263 -2979

152-1325

164-1125

188-1365

93-686

Aspartic Acid

Asp

<64

<56

 <30

<9

 <11

<10

Ethanolamine

EtN

282-3782

256-947

193-643

137-564

158-596

95-471

Histidine

His

145-3833

427-3398

230-2635

268-2147

134-1983

81-1128

Threonine

Thr

25-1217

55-763

30-554