Test Center

My Recent Searches

  • No Recent Search.

My Tests Viewed

  • No Test Viewed.
  • Ordering Info

Carnitine, LC/MS/MS

Test Code


CPT Code(s)



Carnitine, Total; Carnitine, Free; Carnitine, Esters; Esterified/Free Ratio

Patient Preparation

Patient should be in a well-fed state

Preferred Specimen(s)

1 mL serum

Minimum Volume

0.4 mL

Alternative Specimen(s)

Plasma collected in a sodium heparin (green-top) tube

Collection Instructions

Collect blood sample in serum (red-top) tube. Separate serum by centrifugation. Avoid hemolysis. Remove serum and place in plastic tube. Freeze immediately after separation.

Transport Temperature


Specimen Stability

Room temperature: 5 hours
Refrigerated: 5 days
Frozen: 30 days


Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)

Performing Laboratory

Quest Diagnostics Nichols Institute
33608 Ortega Highway
San Juan Capistrano, CA 92690-6130

Setup Schedule

Set up: Mon, Wed, Fri-Sat; Report available: 4-6 days

Reference Range(s)

Carnitine, Total
Adult Male 30-70 µmol/L
Adult Female 25-58 µmol/L
Male ≤17 Years 32-62 µmol/L
Female ≤17 Years 28-59 µmol/L
Carnitine, Free
Adult Male 23-59 µmol/L
Adult Female 19-48 µmol/L
Male ≤17 Years 25-54 µmol/L
Female ≤17 Years 19-51 µmol/L
Carnitine, Esters
Adult Male 4-15 µmol/L
Adult Female 4-13 µmol/L
Male ≤17 Years 4-12 µmol/L
Female ≤17 Years 3-16 µmol/L
Esterified/Free Ratio
Adult Male  0.12-0.39
Adult Female  0.13-0.42
Male ≤17 Years  0.09-0.35
Female ≤17 Years 0.09-0.49

Clinical Significance

Serum carnitine analysis is useful in the diagnosis and monitoring of patients with carnitine deficiency (either primary or secondary). Primary carnitine deficiency is an autosomal recessively inherited genetic condition that affects carnitine uptake by cells and tissues through a defect in the plasma membrane carnitine transporter. Secondary carnitine deficiency can be seen in some disease states or in patients on carnitine-poor diets, but is also seen in a number of metabolic disorders. In these disorders, carnitine complexes with the accumulated substrate of the blocked metabolic step, and the resulting acylcarnitine ester is excreted in the urine, leading to a depletion of carnitine in the patient.

LOINC®' Code(s)

The Result and LOINC information listed below should not be used for electronic interface maintenance with Quest Diagnostics. Please contact the Quest Diagnostics Connectivity Help Desk for more information at 800-697-9302.

NOTE: The codes listed in the table below are not orderable Test Codes.

Result NameLOINC CodeComponent Name
10563Carnitine, Free14286-9Carnitine.free (C0)
10564Carnitine, Esters19074-4Carnitine esters
27135Esterified/Free Ratio40869-0Carnitine esters/Carnitine.free (C0)
989Carnitine, Total14288-5Carnitine

Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

LOINC assignment is based on a combination of test attributes, including the method used by the performing laboratory. For tests not performed by Quest Diagnostics, codes are assigned by the performing laboratory.

* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.