Ordering Recommendation

Useful in the diagnosis of primary carnitine deficiency (carnitine uptake defect) in conjunction with free and total plasma carnitine.




Tandem Mass Spectrometry




2-9 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

Random urine.

Specimen Preparation

Freeze specimen immediately after collection. Transport 5 mL urine. (Min: 2 mL)

Storage/Transport Temperature

CRITICAL FROZEN. Separate specimens must be submitted when multiple tests are ordered.

Unacceptable Conditions

Refrigerated or room temperature specimens.


Ambient: Unacceptable; Refrigerated: Unacceptable; Frozen: 1 month

Reference Interval

Test Number
Reference Interval
0081307 Carnitine, Total, Urine (INACTIVE as of 11/16/20: Refer to 0081308) 0-5 months: 160-1552 µmol/g creatinine
6-23 months: 231-1710 µmol/g creatinine
2 years and older: 73-731 µmol/g creatinine
0081309 Carnitine, Free, Urine (INACTIVE as of 11/16/20: Refer to 0081308) 0-5 months: 16-922 µmol/g creatinine
6-23 months: 37-1066 µmol/g creatinine
2 years and older: 7-407 µmol/g creatinine
  Carnitine, Esterified, Urine 0-5 months: 138-525 µmol/g creatinine
6-23 months: 175-613 µmol/g creatinine
2 years and older: 55-317 µmol/g creatinine
  Carnitine, E/F Ratio, Urine 0-5 months: 0.4-6.8
6-23 months: 0.4-5.0
2 years and older: 0.5-7.3

Interpretive Data

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Compliance Category

Laboratory Developed Test (LDT)


The concentration of esterified carnitine is derived from a mathematical calculation using free and total carnitine.

Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
0081307 Carnitine, Total, Urine 17866-5
0081309 Carnitine, Free, Urine 17867-3
0081310 Carnitine, Esterified, Urine 28589-0
0081311 Carnitine, E/F Ratio, Urine 54442-9
2001266 Creatinine, Urine 2161-8
* 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.


  • L-Carnitine
  • Urinary Carnitine, Quantitative
Carnitine, Free and Total, Urine