Clinics and Departments

Laboratory Services

Lab Dept:

Chemistry

Test Name:

CARNITINE, TOTAL AND FREE

General Information

Lab Order Codes:

CARN

Synonyms:

L-Carnitine

CPT Codes:

82379 – Carnitine (total and free), quantitative, each specimen

Test Includes:

Total carnitine (TC), Free carnitine (FC), Acylcarnitine (AC) Range and AC/FC Ratio

Logistics

Test Indications:

Evaluation of patients with a clinical suspicion of a wide range of inborn errors of metabolism, especially organic acidemias and fatty acid oxidation disorders including primary carnitine deficiency.

Lab Testing Sections:

Chemistry - Sendouts

Referred to:

Mayo Medical Laboratories (MML Test: 60449/CARN)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

2 - 5 days, performed Monday - Friday

Special Instructions:

N/A

Specimen

Specimen Type:

Blood

Container:

Red top, plain, no gel tubes

Draw Volume:

1.5 mL (Minimum: 0.6 mL) blood

Processed Volume:

0.5 mL (Minimum: 0.2 mL) serum

Collection:

Routine venipuncture

Special Processing:

Lab Staff: Centrifuge specimen and remove serum aliquot into a screw-capped round bottom plastic vial. Store and shop at frozen temperatures. Indicate on label “serum”. This assay must be aliquoted into a separate vial and frozen. It should not be combined with other testing.

Patient Preparation:

None

Sample Rejection:

Specimens other than serum, warm specimens; mislabeled or unlabeled specimens

Interpretive

Reference Ranges:

Age

Total Carnitine(TC) Range nmol/mL

Free Carnitine (FC) Range nmol/mL

Acylcarnitine (AC) Range nmol/mL

AC/FC Ratio

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

Table used with permission of Schmidt-Sommerfeld E, Werner E, Penn D: Carnitine plasma concentrations in 353 metabolically healthy children. Eur J Pediatr 147:356-360, 1988 and the European Journal of Pediatrics, Springer-Verlag, New York, Inc., Secaucus, NJ

Interpretation: When abnormal results are detected, a detailed interpretation is given, including an overview of the results and their significance, a correlation to available clinical information, elements of differential diagnosis, recommendations for additional biochemical testing, and a phone number to reach one of the laboratory directors in case the referring physician has additional questions.

Critical Values:

N/A

Limitations:

Determination of urine carnitine concentration concurrently with serum concentration is recommended.

Methodology:

Tandem Mass Spectrometry (MS/MS)

References:

Mayo Medical Laboratories Web Page (October 2010)

Updates:

10/12/2010: Units change, previously reported as umol/L.



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