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Carnitine
Test CodeCARITB
Includes
Carnitine, Total
Carnitine, Free
Carnitine, Esters
Esterified/Free Ratio
Carnitine, Free
Carnitine, Esters
Esterified/Free Ratio
Preferred Specimen
1 mL frozen serum
Patient Preparation
Patient should be in a well-fed state
Minimum Volume
0.5 mL
Other Acceptable Specimens
Plasma collected in: Sodium heparin (green-top) tube
Instructions
Separate serum by centrifugation. Avoid hemolysis. Remove serum and place in plastic tube. Freeze immediately after separation.
Transport Temperature
Frozen
Specimen Stability
Room temperature: 5 hours
Refrigerated: 5 days
Frozen: 30 days
Refrigerated: 5 days
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Moderate and gross hemolysis • Received room temperature
Methodology
Chromatography/Mass Spectrometry
FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
Setup Schedule
P.M. Sets up 4 days a week.
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.