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Test Code AACSF Amino Acids, Quantitative, Spinal Fluid

Reporting Name

Amino Acids, QN, CSF

Useful For

Evaluating patients with possible inborn errors of amino acid metabolism, particularly nonketotic hyperglycinemia (glycine encephalopathy) and serine biosynthesis defects, especially when used in conjunction with concomitantly collected plasma specimens

Testing Algorithm

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

 

For more information see Epilepsy: Unexplained Refractory and/or Familial Testing Algorithm.

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Portions of this test are covered by patents held by Quest Diagnostics

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

CSF


Additional Testing Requirements


This test should be ordered in conjunction with AAQP / Amino Acids, Quantitative, Plasma. The specimens for both tests (AAQP / Amino Acids, Quantitative, Plasma and this test) should be collected at the same time.



Necessary Information


1. Patient's age is required.

2. Include family history, clinical condition (asymptomatic or acute episode), diet, and drug therapy information



Specimen Required


Container/Tube: Sterile vial

Specimen Volume: 0.2 mL

Collection Instructions: Collect specimen from second collection vial.


Specimen Minimum Volume

0.1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
CSF Frozen 14 days

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Reference Values

Amino Acid

Age groups

≤31 days

32 days-23 months

2-18 years

≥19 years

Taurine (Tau)

8-28

4-13

4-10

3-9

Asparagine (Asn)

7-25

5-17

4-12

5-14

Serine (Ser)

43-127

37-87

22-57

18-58

Hydroxyproline (Hyp)

<12

<8

<3

<3

Glycine (Gly)

<60

<27

<20

<28

Glutamine (Gln)

447-1547

384-716

375-770

452-1283

Aspartic Acid (Asp)

<12

<12

<12

<12

Ethanolamine (EtN)

11-152

6-41

7-25

6-24

Histidine (His)

19-63

12-32

9-26

12-36

Threonine (Thr)

35-212

19-89

13-51

13-57

Citrulline (Cit)

<6

<5

<4

<4

Sarcosine (Sar)

<21

<21

<21

<21

Beta-alanine (bAla)

<17

<17

<17

<17

Alanine (Ala)

20-92

18-69

16-54

22-80

Glutamic Acid (Glu)

<12

<4

<3

<2

1-Methylhistidine (1MHis)

<5

<1

<1

<3

3-Methylhistidine (3MHis)

<4

<1

<3

<5

Argininosuccinic Acid (Asa)

<4

<4

<4

<4

Homocitrulline (Hcit)

<1

<1

<1

<1

Arginine (Arg)

7-37

11-36

13-30

14-32

Alpha-aminoadipic Acid (Aad)

<2

<2

<2

<2

Gamma-amino-n-butyric Acid (GABA)

<10

<10

<10

<10

Beta-aminoisobutyric Acid (bAib)

<1

<1

<1

<1

Alpha-amino-n-butyric Acid (Abu)

<21

<7

<5

<10

Hydroxylysine (Hyl)

<1

<1

<1

<1

Proline (Pro)

<14

<4

<4

<2

Ornithine (Orn)

<32

<15

<12

<15

Cystathionine (Cth)

<4

<1

<1

<2

Cystine (Cys)

<3

<3

<3

<3

Lysine (Lys)

16-67

17-41

13-45

23-54

Methionine (Met)

<19

<7

<5

<12

Valine (Val)

16-83

10-36

10-27

13-52

Tyrosine (Tyr)

<70

<22

<16

<65

Isoleucine (Ile)

2-30

2-14

3-11

3-17

Leucine (Leu)

14-72

9-25

8-23

10-53

Phenylalanine (Phe)

9-49

7-18

5-18

8-23

Tryptophan (Trp)

<14

<14

<14

<14

Allo-isoleucine (AlloIle)

<2

<2

<2

<2

 

All results reported in nmol/mL

Day(s) Performed

Monday through Friday

CPT Code Information

82139

LOINC Code Information

Test ID Test Order Name Order LOINC Value
AACSF Amino Acids, QN, CSF 35507-3

 

Result ID Test Result Name Result LOINC Value
50435 Interpretation 49303-1
81934 Taurine 26614-8
30109 Asparagine 26603-1
30108 Serine 22644-9
34566 Hydroxyproline 26596-7
30115 Glycine 22650-6
30111 Glutamine 22641-5
34567 Aspartic Acid 22655-5
34568 Ethanolamine 26593-4
30128 Histidine 9453-2
30107 Threonine 22643-1
30117 Citrulline 22654-8
34569 Sarcosine 26598-3
34570 Beta-alanine 26589-2
30116 Alanine 22657-1
30110 Glutamic Acid 22652-2
34571 1-Methylhistidine 26584-3
34572 3-Methylhistidine 26585-0
34573 Argininosuccinic Acid 40838-5
34576 Homocitrulline 55875-9
30129 Arginine 22656-3
34577 Alpha-aminoadipic Acid 26587-6
34578 Gamma-amino-n-butyric Acid 26594-2
34579 Beta-aminoisobutyric Acid 26590-0
30118 Alpha-amino-n-butyric Acid 26586-8
34580 Hydroxylysine 26595-9
30112 Proline 22645-6
30126 Ornithine 22647-2
34581 Cystathionine 26592-6
30120 Cystine 22653-0
30127 Lysine 22651-4
30121 Methionine 22648-0
30119 Valine 22649-8
30124 Tyrosine 22642-3
30122 Isoleucine 22659-7
30123 Leucine 9412-8
30125 Phenylalanine 22646-4
34582 Tryptophan 26602-3
34583 Allo-isoleucine 22658-9

Clinical Information

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 metabolism have been identified. Amino acid disorders can manifest at any age, but most become evident in infancy or early childhood. These disorders result in the accumulation or deficiency of 1 or more amino acids in biological fluids, which leads to the clinical signs and symptoms of the specific 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 intellectual disabilities and, possibly, death.

 

Cerebrospinal fluid (CSF) specimens are highly informative for a subset of these conditions, such as nonketotic hyperglycinemia and serine biosynthesis defects. CSF specimens are most informative when a plasma specimen is collected at the same time, and the ratio of the amino acid concentrations in CSF to those in plasma is calculated.

Interpretation

When no significant abnormalities are detected, a simple descriptive interpretation is provided. When abnormal results are detected, a detailed interpretation is provided. This interpretation includes an overview of the results and 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, and the telephone number to reach one of the laboratory directors in case the referring physician has additional questions.

Cautions

Proper specimen collection and handling are crucial to achieve reliable results.

 

Blood contamination can interfere with test results.

Method Description

Quantitative analysis of amino acids (AA) is performed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Patient samples are combined with isotopically labeled internal standard. Following protein precipitation, the supernatant is subjected to hydrophilic-interaction liquid chromatography for the separation of isomers with MS/MS detection of the underivatized amino acids. (Unpublished Mayo method)

Report Available

3 to 5 days

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.