Free Carnitine (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 helps assess metabolic health and potential deficiencies."]
Key facts at a glance
- LOINC
- 2042-0
- Short code
- CARN-FREE
- Synonyms
- Carnitine Free SerPl Ql
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube or serum separator tube (SST)
- Units
- N/A
- Ref low
- 25
- Ref high
- 54
- Critical range
- 10 N/A – 100 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Tandem Mass Spectrometry (MS/MS) or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 82379
- SNOMED
- 44598004
- Specimen volume
- 1-2 mL of serum
- Stability
- Serum stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below
- Hemolysis max
- 100
- Lipemia max
- 50
- Icterus max
- 30
- TAT
- 24–96 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order this test to check for conditions affecting fat metabolism, such as carnitine deficiency, mitochondrial disorders, or certain genetic disorders. It may also be used in patients with unexplained muscle weakness, fatigue, or heart issues linked to fatty acid metabolism problems.
What Does a Result Mean?
Results can vary based on individual health, diet, and other factors. Abnormal levels may suggest metabolic issues, but your doctor will interpret results in the context of your overall health and symptoms.
Common Conditions Monitored
This test is often used to monitor patients with conditions like medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, mitochondrial disorders, or those on certain medications that may affect carnitine levels.
Sample Collection & Preparation
A blood sample is drawn from a vein in your arm. The sample is collected in a special tube to separate serum or plasma from blood cells. The lab processes the sample to measure free carnitine levels.
Reference range
Adults: 25-54 µmol/L; Reference ranges vary by age and laboratory methodology. Pediatric ranges are higher than adult ranges.N/A
No special preparation required. Patient should be well-hydrated. Recent carnitine supplementation or dietary intake may affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Free Carnitine
Frequently asked questions
Low levels of free carnitine may indicate a deficiency that could impair energy production in cells, leading to symptoms like muscle weakness, fatigue, or neurological issues. High levels might suggest metabolic overload or certain liver or kidney conditions.
How long does it take to get results?
Can diet affect my carnitine levels?
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 10, 2026. · Read our editorial policy