Quantitative Free and Total Carnitine Analysis (Test 5000)

CPT Code(s): 82379

Service Code (IU Health): 53065504

Ordering Recommendation: This test is intended to be used to monitor carnitine supplementation therapy, to detect secondary carnitine depletion syndromes, and to detect autosomal recessive primary carnitine uptake deficiency.

Synonyms: L-carnitine, plasma carnitine, serum carnitine

Methodology: Tandem mass spectrometry (MS/MS) without derivitization.

Performed: Weekly

Reported: 2-7 days

Patient Preparation: None required

Specimen Type: frozen plasma/serum

Collection Tube (preferred): sodium heparin (green top)

Collection Tube (other acceptable): lithium heparin (green top), serum (red top), EDTA (lavender top)

Processing: Separate plasma/serum from whole blood and transfer to a plastic transport tube and freeze as soon as possible. If multiple different tests are ordered, submitting separate frozen aliquots for each may improve TAT.

Specimen Volume: 0.5 ml (minimum of 0.2 ml)

Storage: Must be stored at -20°C.

Shipment: Ship samples frozen on 3-5 lbs of dry ice in an insulated container using an overnight courier.

Unacceptable Conditions:

• Specimen requirements listed above not met
• Sample fully thawed during shipment
• Sample has excessive hemolysis or clotting
• Sample collected in gel tube (plasma separator tube (PST) or serum separator tube (SST))

Stability: 90 days in the freezer (-20°C).

Reference Interval: by report 

Interpretation: A brief interpretation of results is provided with each test.

The levels of both free and total carnitine are measured in this test. Free carnitine indicates the level of unconjugated analyte, whereas total carnitine is a measure of the level of both free carnitine and conjugated acyl-carnitines present in the specimen.

Limitations: Analyte values can vary as a result of diet, supplementation, and/or maternal affect. In addition, in rare situations, inaccurate results may arise due to interference from competing isobaric compounds.

Results should be interpreted in the context of clinical symptoms and concurrent testing. In the case of a new diagnosis, results should be confirmed with additional biochemical or molecular genetic testing.

This test was developed and its performance characteristics determined by Indiana University Biochemical Genetics Laboratory. It has not been cleared or approved by the U.S. Food and Drug Administration. This test is used for clinical purposes. It should not be regarded as investigational or for research. The laboratory is certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA ’88) as qualified to perform high complexity clinical laboratory testing. CLIA #15D0647198, CAP #1678930

Reference:

Schmidt-Sommerfeld E., et al., Carnitine plasma concentrations in 353 metabolically healthy children., Eur. J. Pediatr., 1988, 147(4): 350-60. (PMID 3396591)

Analytes Reported:

• Free Carnitine (FC)
• Total Carnitine (TC)
• Acyl Carnitine (AC)
• AC/FC Ratio