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Test Id : ACRNS

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Acylcarnitines, Quantitative, Serum

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Overview

Test Catalog

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

Diagnosis of fatty acid oxidation disorders and several organic acidurias using serum specimens

 

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

Method Name
A short description of the method used to perform the test

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

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Acylcarnitines, Quantitative, S

Aliases
Lists additional common names for a test, as an aid in searching

2-Methyl-3-hydroxybutyryl CoA Dehydrogenase Deficiency

2-Methylbutyryl-CoA Dehydrogenase Deficiency

3-Hydroxy-3-Methylglutaryl-CoA (HMG-CoA) Lyase Deficiency

3-Methylcrotonyl Carboxylase Deficiency

3-Methylglutaconic Aciduria Type 1

3-Methylglutaconic Aciduria Type I

3-Methylglutaconyl-CoA Hydratase Deficiency

Beta-ketothiolase Deficiency

Biotinidase (Multiple Carboxylase) Deficiency

Carnitine-acylcarnitine Translocase (CACT) Deficiency

CPT-II (Carnitine Palmitoyl Transferase Deficiency Type II)

Electron-Transfer Flavoprotein (ETF) Deficiency

Formiminoglutamic Aciduria (FIGLU)

Formiminotransferase (FIGLU) Deficiency

Glutaric Acidemia (GA)

Glutaric Acidemia Type I (GA I)

Glutaric Acidemia Type II (GA II)

Glutaryl-CoA Dehydrogenase (GCDH) Deficiency

Holocarboxylase Synthetase Deficiency

Isobutyryl-CoA Dehdrogenase (IBDH) Deficiency

Isovaleric Acidemia (IVA)

Long-Chain 3-Hydroxyacyl-CoA Dehydrogenase (LCHAD) Deficiency

MADD (Multiple Acyl-CoA Dehydrogenase Deficiency)

Malonic aciduria

Medium-Chain Acyl-CoA Dehydrogenase (MCAD) Deficiency

Methylmalonic Acidemia

Methylmalonic Aciduria (MMA)

Multiple Acyl-CoA Dehydrogenase Deficiency (MADD)

Propionic Acidemia (PA)

S/MCHAD (Short/Medium-Chain 3-Hydroxyacyl-CoA Dehydrogenase) Deficiency

SCAD (Short-Chain Acyl-CoA Dehydrogenase) Deficiency

Short/Medium-Chain 3-Hydroxyacyl-CoA Dehydrogenase (S/MCHAD) Deficiency

Succinyl-CoA Ligase (SUCLA2) Deficiency

SUCLA2 (Succinyl-CoA Ligase) Deficiency

Trifunctional Protein (TFP) Deficiency

Very Long-Chain Acyl-CoA Dehydrogenase (VLCAD) Deficiency

Specimen Type
Describes the specimen type validated for testing

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
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Patient Preparation: Collect specimen just prior to a scheduled meal or feeding.

Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.1 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial.

Forms

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.04 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

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

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

Diagnosis of fatty acid oxidation disorders and several organic acidurias using serum specimens

 

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

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

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.(1) 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 can be measured by tandem mass spectrometry. 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 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.

 

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.

 

The following disorders are detectable by acylcarnitine analysis. However, further confirmatory testing is required for most of these conditions because an acylcarnitine profile can be suggestive of more than one condition.

 

Fatty Acid Oxidation Disorders:

-Carnitine palmitoyltransferase I deficiency

-Medium-chain 3-ketoacyl-CoA thiolase deficiency

-Dienoyl-CoA reductase deficiency

-Short-chain acyl-CoA dehydrogenase deficiency

-Medium/Short-chain 3-hydroxyacyl-CoA dehydrogenase deficiency

-Medium-chain acyl-CoA dehydrogenase) deficiency

-Long-chain 3-hydroxyacyl-CoA dehydrogenase) deficiency and trifunctional protein deficiency

-Very long-chain acyl-CoA dehydrogenase deficiency

-Carnitine palmitoyl transferase type II deficiency

-Carnitine-acylcarnitine translocase deficiency

-Electron transfer flavoprotein (ETF) deficiency, ETF-dehydrogenase deficiency (multiple acyl-CoA dehydrogenase deficiency; 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)

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.

< or =7 days (nmol/mL)

8 days-7 years

(nmol/mL)

> or =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
Provides information to assist in interpretation of the test results

An interpretive report will be 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.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

In a few instances, false-negative results occur in the analysis of acylcarnitine profiles. For some disorders, such as medium-chain acyl-CoA dehydrogenase deficiency, the calculation of ratios between different acylcarnitine species provides a discriminate factor to overcome such problems. Where applicable, the calculation of such ratios will be incorporated in the routine acylcarnitine analysis. Informative profiles may also not be detected in some disorders where the accumulation of diagnostic acylcarnitines is a reflection of the residual activity of the defective enzyme, the dietary load of precursors, and the anabolic/catabolic and treatment statuses of a patient.

 

Patients with carnitine deficiency may not exhibit abnormally high acylcarnitine concentrations. If the results are indicative for carnitine deficiency, the interpretation will include a remark that this limits the diagnostic value of the test and repeat analysis may be considered following carnitine supplementation.

 

Follow-up testing such as in vitro enzyme assays or molecular genetic testing may be recommended following abnormal acylcarnitine results. It is not advisable to intentionally stress the patient's metabolism (eg, fasting test) prior to specimen collection for acylcarnitine analysis.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Miller MJ, Cusmano-Ozog K, Oglesbee D, Young S; ACMG Laboratory Quality Assurance Committee. Laboratory analysis of acylcarnitines, 2020 update: a technical standard of the American College of Medical Genetics and Genomics (ACMG). Genet Med. 2021;23(2):249-258

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

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

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

5. Elizondo G, Matern D, Vockley J, Harding CO, Gillingham MB. Effects of fasting, feeding and exercise on plasma acylcarnitines among subjects with CPT2D, VLCADD and LCHADD/TFPD. Mol Genet Metab. 2020;131(1-2):90-97

Method Description
Describes how the test is performed and provides a method-specific reference

To 20 mcL of serum, 6 internal standards of known concentration (d3-acetylcarnitine, d3-propionylcarnitine, d7-butyrylcarnitine, d3-octanoylcarnitine, d3-dodecanoylcarnitine, and d3-palmitoyl-carnitine) and acetonitrile for deproteinization are added. Following shaking for 30 minutes and centrifugation, the supernate is dried and then treated with n-butanolic HCl yielding the acylcarnitines, which are analyzed as their n-butylesters by electrospray ionization tandem mass spectrometry. The concentrations of the analytes are established by computerized comparison of these analytes' ion intensities to those of the closest internal standard.(Van Hove JL, Kahler SG, Feezor MD, et al. Acylcarnitines in plasma and blood spots of patients with long-chain 3-hydroxyacylcoenzyme A dehydrogenase deficiency. J Inherit Metab Dis. 2000;23(6):571-582; Miller MJ, Cusmano-Ozog K, Oglesbee D, Young S; ACMG Laboratory Quality Assurance Committee. Laboratory analysis of acylcarnitines, 2020 update: a technical standard of the American College of Medical Genetics and Genomics [ACMG]. Genet Med. 2021;23[2]:249-258)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

2 to 5 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 month

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

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Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

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.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

82017

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
ACRNS Acylcarnitines, Quantitative, S 43433-2
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
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 90237-9
92149 Salicylcarnitine 90238-7
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
92156 Methylmalonyl-/succinylcarn, C4-DC 51415-8
92157 3-OH-decenoylcarnitine, C10:1-OH 82478-9
92155 Decanoylcarnitine, C10 30327-1
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

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