Free Carnitine in Serum/Plasma
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 and detect conditions affecting fat metabolism."]
Key facts at a glance
- LOINC
- 14286-9
- Short code
- C0
- Synonyms
- Carnitine Free SerPl-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube or serum separator tube (SST); avoid hemolysis
- Units
- N/A
- Ref low
- 20
- Ref high
- 60
- Critical range
- 10 N/A – 100 N/A
- 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); Enzymatic methods also available
- CPT
- 82379
- SNOMED
- 395145001
- Specimen volume
- 1-2 mL serum (minimum 0.5 mL)
- Stability
- Room temperature: 4 hours; Refrigerated (2-8°C): 1 week; Frozen (-20°C or below): 3 months
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 24–168 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like muscle weakness, fatigue, or unexplained weight changes, or if you have conditions such as mitochondrial disorders, liver disease, or kidney problems that may affect carnitine levels.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for a few hours before the blood draw if your test involves fasting. Avoid strenuous exercise or certain medications that could influence results for 24 hours before testing.
What Happens During the Test
A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause significant discomfort. The blood sample will be sent to a lab for analysis using a high-performance liquid chromatography (HPLC) method.
What the Results Mean
Results are typically reported as a concentration value (in micromoles per liter or similar units). Abnormal levels may indicate metabolic issues, but your doctor will interpret results in the context of your overall health and symptoms.
Reference range
Adults: 20-60 µmol/L (varies by laboratory and methodology); Pediatric ranges differ by age. Free carnitine (C0) levels are typically higher in males than females and decrease with age.N/A
No fasting required. Patient should avoid heavy exercise prior to specimen collection. Dietary intake and supplementation status should be documented as results are influenced by diet and carnitine supplements.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low free carnitine levels may suggest deficiencies in fat metabolism, mitochondrial dysfunction, or conditions like carnitine palmitoyltransferase deficiency. High levels can sometimes indicate liver disease, kidney problems, or certain metabolic disorders. Always discuss results with your healthcare provider, as they will consider your medical history and symptoms for a proper evaluation.
Short name
Free Carnitine
Frequently asked questions
How long does it take to get my test results?
Can I eat or drink anything before this test?
Is there anything I should avoid doing before the 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 15, 2026. · Read our editorial policy