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Order Code LAB1248 Carnitine, Plasma

Additional Codes

Mayo Test ID
CARN

Reporting Name

Carnitine, P

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 plasma specimens

Specimen Type

Plasma


Necessary Information


Patient's age is required.



Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: Lavender top (EDTA), green top (lithium heparin)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot plasma into a plastic vial


Specimen Minimum Volume

0.2 mL

Specimen Stability Information

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

Reject Due To

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

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;147:356-360

Used with permission of European Journal of Pediatrics.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Day(s) Performed

Monday through Friday

Method Name

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

CPT Code Information

82379

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)