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Test Code ACRNS Acylcarnitines, Quantitative, Serum


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: Serum

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 0.1 mL

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


Secondary ID

60644

Useful For

Diagnosis of fatty acid oxidation disorders and several organic acidurias in serum 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)

Method Name

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

Reporting Name

Acylcarnitines, Quantitative, S

Specimen Type

Serum

Specimen Minimum Volume

0.04 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Frozen (preferred) 60 days
  Refrigerated  21 days
  Ambient  72 hours

Reject Due To

Hemolysis

Mild OK; Gross OK

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross OK

Other

NA

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/or 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/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.

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

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

Day(s) and Time(s) Performed

Monday through Friday; 8 a.m.

Analytic Time

2 days (not reported on Sunday)

Performing Laboratory

Mayo Medical Laboratories in Rochester

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
ACRNS Acylcarnitines, Quantitative, S 43433-2

 

Result ID Test Result Name Result LOINC Value
92134 Acetylcarnitine, C2 30191-1
92135 Acrylylcarnitine, C3:1 43235-1
92136 Propionylcarnitine, C3 30551-6
92137 Formiminoglutamate, FIGLU 79628-4
92138 Iso-/Butyrylcarnitine, C4 35655-0
92139 Tiglylcarnitine, C5:1 51416-6
92140 Isovaleryl-/2-Methylbutyrylcarn C5 30531-8
92141 3-OH-iso-/butyrylcarnitine, C4-OH 39000-5
92142 Hexenoylcarnitine, C6:1 74540-6
92143 Hexanoylcarnitine, C6 30358-6
92144 3-OH-isovalerylcarnitine, C5-OH 39001-3
92145 Benzoylcarnitine 39615-0
92146 Heptanoylcarnitine, C7 55871-8
92147 3-OH-hexanoylcarnitine, C6-OH 30236-4
92148 Phenylacetylcarnitine No LOINC Needed
92149 Salicylcarnitine No LOINC Needed
92150 Octenoylcarnitine, C8:1 30541-7
92151 Octanoylcarnitine, C8 30540-9
92152 Malonylcarnitine, C3-DC 55940-1
92153 Decadienoylcarnitine, C10:2 53471-9
92154 Decenoylcarnitine, C10:1 30328-9
92155 Decanoylcarnitine, C10 30327-1
92156 Methylmalonyl-/succinylcarn, C4-DC 51415-8
92157 3-OH-decenoylcarnitine, C10:1-OH 82478-9
92158 Glutarylcarnitine, C5-DC 30349-5
92159 Dodecenoylcarnitine, C12:1 30332-1
92160 Dodecanoylcarnitine, C12 30331-3
92161 3-Methylglutarylcarnitine, C6-DC 39002-1
92162 3-OH-dodecenoylcarnitine, C12:1-OH 59195-8
92163 3-OH-dodecanoylcarnitine, C12-OH 30233-1
92164 Tetradecadienoylcarnitine, C14:2 30564-9
92165 Tetradecenoylcarnitine, C14:1 30566-4
92166 Tetradecanoylcarnitine, C14 30565-6
92167 Octanedioylcarnitine, C8-DC 39014-6
92168 3-OH-tetradecenoylcarnitine C14:1OH 30190-3
92169 3-OH-tetradecanoylcarnitine, C14-OH 30238-0
92170 Hexadecenoylcarnitine, C16:1 30357-8
92171 Hexadecanoylcarnitine, C16 30356-0
92172 3-OH-hexadecenoylcarnitine,C16:1-OH 30235-6
92173 3-OH-hexadecanoylcarnitine, C16-OH 30234-9
92174 Octadecadienoylcarnitine, C18:2 30534-2
92175 Octadecenoylcarnitine, C18:1 30542-5
92176 Octadecanoylcarnitine, C18 30560-7
92177 Dodecanedioylcarnitine, C12-DC 55855-1
92178 3-OH-octadecadienoylcarn, C18:2-OH 30237-2
92179 3-OH-octadecenoylcarnitine C18:1-OH 30312-3
92180 3-OH-octadecanoylcarnitine, C18-OH 35656-8
92181 Comment (ACRNS) 46252-3