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Test Code LAB1231821 Carnitine, Serum

Important Note

Mayo's test code: CARNS

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Reporting Name

Carnitine, S

Specimen Type

Serum


Necessary Information


Patient's age is required.



Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL Serum

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.


Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

Specimen Stability Information

Specimen Type Temperature Time
Serum Frozen (preferred) 60 days
  Refrigerated  21 days
  Ambient  7 days

Specimen Minimum Volume

Serum: 0.2 mL

Day(s) Performed

Monday through Friday

Specimen Retention Time

1 month

Report Available

3 to 5 days

Reference Values

 

Total carnitine (TC)

Free carnitine (FC)

Acylcarnitine (AC)

AC/FC Ratio

Age Group

Range*

Range*

Range*

Range

≤1 day

23-68

12-36

7-37

0.4-1.7

2-7 days

17-41

10-21

3-24

0.2-1.4

8-31 days

19-59

12-46

4-15

0.1-0.7

32 days-12 months

38-68

27-49

7-19

0.2-0.5

13 months-6 years

35-84

24-63

4-28

0.1-0.8

7-10 years

28-83

22-66

3-32

0.1-0.9

11-17 years

34-77

22-65

4-29

0.1-0.9

≥18 years

34-78

25-54

5-30

0.1-0.8

 

*Values expressed as nmol/mL

Schmidt-Sommerfeld E, Werner E, Penn D. Carnitine plasma concentrations in 353 metabolically healthy children. Eur J Pediatr. 1988;147(4):356-360

Used with permission of European Journal of Pediatrics.

Useful For

Evaluation of patients with a clinical suspicion of a wide range of conditions including organic acidemias, fatty acid oxidation disorders, and primary carnitine deficiency using serum specimens

CPT Code Information

82379

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CARNS Carnitine, S 97182-0

 

Result ID Test Result Name Result LOINC Value
32045 Total 14288-5
32046 Free (FC) 14286-9
32047 Acylcarnitine (AC) 14282-8
32048 AC/FC Ratio 30193-7
32049 Interpretation 59462-2

Method Description

Free and total carnitines are measured by tandem mass spectrometry (MS/MS) stable isotope dilution analysis. Hydrolysis enables measurement of total carnitine, and esterified carnitine (acylcarnitine) is calculated as the difference between the total and free carnitine. Quantification is enabled using deuterium-labeled carnitine (d3-carnitine) added as internal standard. A selected reaction monitoring experiment is performed by MS/MS. The first mass spectrometer detects carnitine and d3-carnitine precursors and transmits them to a collision cell within the mass spectrometer where they are fragmented. Specific fragments derived from the carnitine and internal standard are monitored in the second mass spectrometer.(Stevens RD, Hillman SL, Worthy S, Sanders D, Millington DS. Assay for free and total carnitine in human plasma using tandem mass spectrometry. Clin Chem. 2000;46[5]:727-729; 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)