Carnitine, Free & Total (Includes Carnitine, Esterified)
Ordering Recommendation

Useful in the diagnosis of primary carnitine deficiency (carnitine uptake defect). Monitor carnitine status.

Tandem Mass Spectrometry
1-4 days
New York DOH Approval Status
This test is New York DOH approved.
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Green (sodium or lithium heparin). Also acceptable: Plain red. 
Specimen Preparation
Separate serum or plasma from cells ASAP or within 2 hours of collection. Transfer 0.5 mL serum or plasma to an ARUP Standard Transport Tube and freeze immediately. (Min: 0.2 mL) Avoid hemolysis. 
Storage/Transport Temperature
CRITICAL FROZEN. Separate specimens must be submitted when multiple tests are ordered. 
Unacceptable Conditions
Room temperature specimens. Specimens refrigerated greater than 12 hours. 
After separation from cells: Ambient: Unacceptable; Refrigerated: 12 hours; Frozen: 1 month (avoid repeated freeze/thaw cycles) 
Reference Interval
AgeFree CarnitineTotal CarnitineEsterified CarnitineRatio Esterified: Free
1 - 31 days15 - 55 µmol/L21 - 83 µmol/L4 - 29 µmol/L0.2 - 0.8
32 days-12 months29 - 61 µmol/L38 - 73 µmol/L7 - 24 µmol/L0.1 - 0.8
13 months - 6 years25 - 55 µmol/L35 - 90 µmol/L4 - 36 µmol/L0.1 - 0.8
7 years -20 years22 - 63 µmol/L31 - 78 µmol/L3 - 38 µmol/L0.1 - 0.9
21 years or older25 - 60 µmol/L34 - 86 µmol/L5 - 29 µmol/L0.1 - 1.0

Interpretive Data

Compliance Statement B: For laboratory developed tests not using a RUO kit, and for FDA approved, cleared or 510(k) exempt assays with alterations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

The concentration of esterified carnitine is derived from a mathematical calculation using free and total carnitine.
Hotline History
Component Test Code*Component Chart NameLOINC
0080064Carnitine, Esterified14282-8
0080066Carnitine, Free14286-9
0080067Carnitine, Total14288-5
0081148Carnitine Esterified/Free (Ratio)40869-0
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • Esterified carnitine
  • Free and Total Carnitine
  • L-Carnitine Free and Total