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Test Code ACRN Acylcarnitines, Quantitative, Plasma

Reporting Name

Acylcarnitines, Quantitative, P

Useful For

Diagnosis of fatty acid oxidation disorders and several organic acidurias in plasma specimens

 

Evaluating treatment during follow-up of patients with fatty acid beta-oxidation disorders and several organic acidurias

Testing Algorithm

The following algorithms are available in Special Instructions:

-Newborn Screening Follow-up for Elevations of C8, C6, and C10 Acylcarnitines (also applies to any plasma or serum C8, C6, and C10 acylcarnitine elevations)

-Newborn Screening Follow-up for Isolated C4 Acylcarnitine Elevations (also applies to any plasma or serum C4 acylcarnitine elevation)

-Newborn Screening Follow-up for Isolated C5 Acylcarnitine Elevations (also applies to any plasma or serum C5 acylcarnitine elevation)

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Plasma


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


Specimen Type: Plasma

Collection Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: Lavender top (EDTA) or lithium heparin

Submission Container/Tube: Plastic vial

Specimen Volume: 0.1 mL

Collection Instructions: Draw specimen just prior to a scheduled meal or feeding.


Specimen Minimum Volume

0.04 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Frozen (preferred) 92 days
  Refrigerated  64 days
  Ambient  8 days

Day(s) and Time(s) Performed

Monday through Friday; 8 a.m.

Test Classification

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

CPT Code Information

82017

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ACRN Acylcarnitines, Quantitative, P 43433-2

 

Result ID Test Result Name Result LOINC Value
82413 Acylcarnitines, Quantitative, P 46252-3
10288 Acetylcarnitine, C2 30191-1
36497 Acrylylcarnitine, C3:1 43235-1
10289 Propionylcarnitine, C3 30551-6
36498 Formiminoglutamate, FIGLU 79628-4
10290 Iso-/Butyrylcarnitine, C4 43243-5
36499 Tiglylcarnitine, C5:1 51416-6
10293 Isovaleryl-/2-Methylbutyrylcarn C5 30531-8
36500 3-OH-iso-/butyrylcarnitine, C4-OH 39000-5
36501 Hexenoylcarnitine, C6:1 74540-6
10295 Hexanoylcarnitine, C6 30358-6
36502 3-OH-isovalerylcarnitine, C5-OH 39001-3
36503 Benzoylcarnitine 39615-0
36504 Heptanoylcarnitine, C7 55871-8
10297 3-OH-hexanoylcarnitine, C6-OH 30236-4
36505 Phenylacetylcarnitine In Process
36506 Salicylcarnitine In Process
10298 Octenoylcarnitine, C8:1 30541-7
10299 Octanoylcarnitine, C8 30540-9
36507 Malonylcarnitine, C3-DC 55940-1
36508 Decadienoylcarnitine, C10:2 53471-9
10301 Decenoylcarnitine, C10:1 30328-9
10302 Decanoylcarnitine, C10 30327-1
36509 Methylmalonyl-/succinylcarn, C4-DC 51415-8
36510 3-OH-decenoylcarnitine, C10:1-OH 82478-9
10304 Glutarylcarnitine, C5-DC 30349-5
10305 Dodecenoylcarnitine, C12:1 30332-1
10306 Dodecanoylcarnitine, C12 30331-3
36511 3-Methylglutarylcarnitine, C6-DC 39002-1
36512 3-OH-dodecenoylcarnitine, C12:1-OH 59195-8
10307 3-OH-dodecanoylcarnitine, C12-OH 30233-1
10308 Tetradecadienoylcarnitine, C14:2 30564-9
10309 Tetradecenoylcarnitine, C14:1 30566-4
10310 Tetradecanoylcarnitine, C14 30565-6
36513 Octanedioylcarnitine, C8-DC 39014-6
10311 3-OH-tetradecenoylcarnitine C14:1OH 30190-3
10312 3-OH-tetradecanoylcarnitine, C14-OH 30238-0
10313 Hexadecenoylcarnitine, C16:1 30357-8
10314 Hexadecanoylcarnitine, C16 30356-0
10315 3-OH-hexadecenoylcarnitine,C16:1-OH 30235-6
10316 3-OH-hexadecanoylcarnitine, C16-OH 30234-9
10317 Octadecadienoylcarnitine, C18:2 30534-2
10318 Octadecenoylcarnitine, C18:1 30542-5
10319 Octadecanoylcarnitine, C18 30560-7
36514 Dodecanedioylcarnitine, C12-DC 55855-1
10320 3-OH-octadecadienoylcarn, C18:2-OH 30237-2
10321 3-OH-octadecenoylcarnitine C18:1-OH 30312-3
36515 3-OH-octadecanoylcarnitine, C18-OH 35656-8
10322 Comment (ACRN) 48767-8

Clinical Information

Acylcarnitine analysis enables the diagnosis of many disorders of fatty acid oxidation and several organic acidurias, as relevant enzyme deficiencies cause the accumulation of specific acyl-CoAs. Fatty acid oxidation (FAO) plays a major role in energy production during periods of fasting. When the body's supply of glucose is depleted, fatty acids are mobilized from adipose tissue, taken up by the liver and muscles, and oxidized to acetyl-CoA. In the liver, acetyl-CoA is the building block for the synthesis of ketone bodies, which enter the blood stream and provide an alternative substrate for production of energy in other tissues when the supply of glucose is insufficient to maintain a normal level of energy. The acyl groups are conjugated with carnitine to form acylcarnitines, which are measured by tandem mass spectrometry (MS/MS). Diagnostic results are usually characterized by a pattern of significantly elevated acylcarnitine species compared to normal and disease controls.

 

In general, more than 20 inborn errors of metabolism can be identified using this method including FAO disorders and organic acidurias. The major clinical manifestations associated with individual FAO disorders include hypoketotic hypoglycemia, variable degrees of liver disease and failure, skeletal myopathy, dilated/hypertrophic cardiomyopathy, and sudden or unexpected death. Organic acidurias also present as acute life-threatening events early in life with metabolic acidosis, increased anion gap, and neurologic distress. Patients with any of these disorders are at risk of developing fatal metabolic decompensations following the acquisition of even common infections. Once diagnosed, these disorders can be treated by avoidance of fasting, special diets, and cofactor and vitamin supplementation.

 

Analysis of acylcarnitines in blood and bile spots represents the first level of evaluation of a complete postmortem investigation of a sudden or unexpected death of an individual. Additional confirmatory testing is recommended. The diagnosis of an underlying FAO disorder or organic aciduria allows genetic counseling of the family, including the possible option of future prenatal diagnosis, and testing of at-risk family members of any age.

 

Disorders Detectable by Acylcarnitine Analysis*

Fatty Acid Oxidation Disorders:

-Carnitine palmitoyltransferase I (CPTI) deficiency

-Medium-chain 3-ketoacyl-CoA thiolase (MCKAT) deficiency

-Dienoyl-CoA reductase deficiency

-Short-chain acyl-CoA dehydrogenase (SCAD) deficiency

-Medium/Short-chain 3-hydroxyacyl-CoA dehydrogenase (M/SCHAD) deficiency

-Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency

-Long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency & trifunctional protein deficiency

-Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency

-Carnitine palmitoyl transferase type II (CPT-II) deficiency

-Carnitine-acylcarnitine translocase (CACT) deficiency

-Electron transfer flavoprotein (ETF) deficiency, ETF-dehydrogenase deficiency (multiple acyl-CoA dehydrogenase deficiency [MADD]; glutaric acidemia type II) 

Organic Acid Disorders:

-Glutaryl-CoA dehydrogenase deficiency (glutaric acidemia type I)

-Propionic Acidemia

-Methylmalonic Acidemia

-Isovaleric Acidemia

-3-hydroxy-3-methylglutaryl-CoA carboxylase deficiency

-3-Methylcrotonyl carboxylase deficiency

-Biotinidase deficiency

-Multiple carboxylase deficiency

-Isobutyryl-CoA dehydrogenase deficiency

-2-Methylbutyryl-CoA dehydrogenase deficiency

-Beta-ketothiolase deficiency

-Malonic aciduria

-Ethylmalonic encephalopathy

-Glutamate formiminotransferase deficiency (Formiminoglutamic aciduria)

*Further confirmatory testing is required for most of these conditions because an acylcarnitine profile can be suggestive of more than 1 condition.

Interpretation

An interpretive report is provided. The individual quantitative results support the interpretation of the acylcarnitine profile but are not diagnostic by themselves. The interpretation is based on pattern recognition.

 

Abnormal results are not sufficient to conclusively establish a diagnosis of a particular disease. To verify a preliminary diagnosis based on an acylcarnitine analysis, independent biochemical (eg, in vitro enzyme assay) or molecular genetic analyses are required.

 

For information on the follow-up of specific acylcarnitine elevations, see Special Instructions for the following algorithms:

-Newborn Screening Follow-up for Elevations of C8, C6, and C10 Acylcarnitines (also applies to any plasma or serum C8, C6, and C10 acylcarnitine elevations)

-Newborn Screening Follow-up for Isolated C4 Acylcarnitine Elevations (also applies to any plasma or serum C4 acylcarnitine elevation)

-Newborn Screening Follow-up for Isolated C5 Acylcarnitine Elevations (also applies to any plasma or serum C5 acylcarnitine elevation)

Clinical Reference

1. Matern D: Acylcarnitines, including in vitro loading tests. In Laboratory Guide to the Methods in Biochemical Genetics. Edited by N Blau, M Duran, KM Gibson. Springer Verlag 2008 pp 171-206

2. Rinaldo P, Cowan TM, Matern D: Acylcarnitine profile analysis. Genet Med 2008;10:151-156

3. Smith EH, Matern D: Acylcarnitine analysis by tandem mass spectrometry. Curr Protoc Hum Genet 2010;Chapter 17:Unit 17.8.1-20

Analytic Time

2 days (not reported on Sunday)

Reject Due To

Hemolysis

Mild OK; Gross OK

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross OK

Other

NA

Method Name

Flow Injection Analysis-Tandem Mass Spectrometry (FIA-MS/MS)

Reference Values

 

≤7 days (nmol/mL)

8 days-7 years

(nmol/mL)

≥8 years

(nmol/mL)

Acetylcarnitine, C2

2.14-15.89

2.00-27.57

2.00-17.83

Acrylylcarnitine, C3:1

<0.04

<0.05

<0.07

Propionylcarnitine, C3

<0.55

<1.78

<0.88

Formiminoglutamate, FIGLU

<0.43

<0.08

<0.14

Iso-/Butyrylcarnitine, C4

<0.46

<1.06

<0.83

Tiglylcarnitine, C5:1

<0.05

<0.09

<0.11

Isovaleryl-/2-Methylbutyrylcarn C5

<0.38

<0.63

<0.51

3-OH-iso-/butyrylcarnitine, C4-OH

<0.13

<0.51

<0.18

Hexenoylcarnitine, C6:1

<0.12

<0.10

<0.15

Hexanoylcarnitine, C6

<0.14

<0.23

<0.17

3-OH-isovalerylcarnitine, C5-OH

<0.08

<0.12

<0.10

Benzoylcarnitine

<0.13

<0.07

<0.10

Heptanoylcarnitine, C7

<0.05

<0.05

<0.06

3-OH-hexanoylcarnitine, C6-OH

<0.08

<0.19

<0.09

Phenylacetylcarnitine

<0.15

<0.22

<0.29

Salicylcarnitine

<0.08

<0.09

<0.09

Octenoylcarnitine, C8:1

<0.48

<0.91

<0.88

Octanoylcarnitine, C8

<0.19

<0.45

<0.78

Malonylcarnitine, C3-DC

<0.09

<0.14

<0.26

Decadienoylcarnitine, C10:2

<0.11

<0.12

<0.26

Decenoylcarnitine, C10:1

<0.25

<0.46

<0.47

Decanoylcarnitine, C10

<0.27

<0.91

<0.88

Methylmalonyl-/succinylcarn, C4-DC

<0.05

<0.05

<0.05

3-OH-decenoylcarnitine, C10:1-OH

<0.12

<0.12

<0.13

Glutarylcarnitine, C5-DC

<0.06

<0.10

<0.11

Dodecenoylcarnitine, C12:1

<0.19

<0.37

<0.35

Dodecanoylcarnitine, C12

<0.18

<0.35

<0.26

3-Methylglutarylcarnitine, C6-DC

<0.28

<0.21

<0.43

3-OH-dodecenoylcarnitine, C12:1-OH

<0.11

<0.10

<0.13

3-OH-dodecanoylcarnitine, C12-OH

<0.06

<0.09

<0.08

Tetradecadienoylcarnitine, C14:2

<0.09

<0.13

<0.18

Tetradecenoylcarnitine, C14:1

<0.16

<0.35

<0.24

Tetradecanoylcarnitine, C14

<0.11

<0.15

<0.12

Octanedioylcarnitine, C8-DC

<0.25

<0.19

<0.19

3-OH-tetradecenoylcarnitine C14:1OH

<0.06

<0.18

<0.13

3-OH-tetradecanoylcarnitine, C14-OH

<0.04

<0.05

<0.08

Hexadecenoylcarnitine, C16:1

<0.15

<0.21

<0.10

Hexadecanoylcarnitine, C16

<0.36

<0.52

<0.23

3-OH-hexadecenoylcarnitine,C16:1-OH

<0.78

<0.36

<0.06

3-OH-hexadecanoylcarnitine, C16-OH

<0.10

<0.07

<0.06

Octadecadienoylcarnitine, C18:2

<0.12

<0.31

<0.24

Octadecenoylcarnitine, C18:1

<0.25

<0.45

<0.39

Octadecanoylcarnitine, C18

<0.10

<0.12

<0.14

Dodecanedioylcarnitine, C12-DC

<0.10

<0.04

<0.04

3-OH-octadecadienoylcarn, C18:2-OH

<0.04

<0.06

<0.06

3-OH-octadecenoylcarnitine C18:1-OH

<0.03

<0.04

<0.06

3-OH-octadecanoylcarnitine, C18-OH

<0.03

<0.05

<0.03