Free Carnitine (Serum)
This test measures the amount of free carnitine, a compound that helps transport fatty acids into cells for energy production, in your blood.
["Free carnitine levels can help assess metabolic health, especially in conditions affecting fat metabolism."]
Key facts at a glance
- LOINC
- 24452-5
- Short code
- C0-TISS
- Synonyms
- Carnitine Free Tiss-sCnt
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube (no anticoagulant) or serum separator tube (SST); tissue specimens require sterile containers with saline-moistened gauze
- Units
- N/A
- Ref low
- 1500
- Ref high
- 4500
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Tandem Mass Spectrometry (MS/MS) or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 82017
- SNOMED
- 74021004
- Specimen volume
- 1-2 mL serum; tissue biopsy minimum 10-50 mg
- Stability
- Serum: stable for 7 days at 2-8°C, 30 days at -20°C; Tissue: stable for 7 days at 2-8°C, longer at -80°C
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 48–168 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order this test to evaluate metabolic disorders, such as carnitine deficiency, or to monitor conditions like mitochondrial disorders, muscle disorders, or certain types of heart disease. It may also be used in the context of nutritional support or before certain treatments that affect metabolism.
What Does It Measure?
Free carnitine is a form of carnitine that circulates freely in your blood. It plays a critical role in breaking down fats for energy. Low levels may indicate problems with fat metabolism or certain genetic or acquired conditions.
Sample Collection and Preparation
A blood sample is typically drawn from a vein in your arm. The sample is collected in a special tube and sent to the lab for analysis. Free carnitine levels are measured using a specialized laboratory method, often involving high-performance liquid chromatography (HPLC).
What Might Affect Results?
Several factors can influence free carnitine levels, including diet (especially high-fat or protein intake), certain medications (like some antibiotics, steroids, or medications for diabetes), and underlying health conditions. Recent exercise or fasting can also temporarily affect results.
Reference range
Reference ranges vary by tissue type (skeletal muscle, cardiac muscle, liver); consult laboratory-specific reference values. Generally, skeletal muscle free carnitine: 1500-4500 nmol/g tissue; cardiac muscle: 2000-6000 nmol/g tissueN/A
No special preparation required for serum specimen. For tissue biopsy, fasting status and recent exercise should be documented as they affect carnitine levels
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Free Carnitine
Frequently asked questions
What Does It Mean If My Levels Are Abnormal?
How Often Should I Get This Test?
Can I Prepare for This Test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy