Free Carnitine (Serum/Plasma)
This test measures the amount of free carnitine, a compound that helps transport fatty acids into cells for energy production. It may be checked if you have symptoms of metabolic or muscle disorders.
["Free carnitine helps cells use fat for energy and may be checked for metabolic or muscle-related conditions."]
Key facts at a glance
- LOINC
- 109068-7
- Short code
- C0
- Synonyms
- Carnitine Free Msmt SerPl
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube or serum separator tube (SST)
- Units
- N/A
- Ref low
- 20
- Ref high
- 50
- Critical range
- 10 N/A – 100 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) or Enzymatic Colorimetric Assay
- CPT
- 82379
- SNOMED
- 44875002
- Specimen volume
- 1 mL serum
- Stability
- Stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 150
- Icterus max
- 50
- TAT
- 24–72 hours
- Order
- routine
Why This Test Is Done
Your healthcare provider may order a free carnitine test if you have symptoms like muscle weakness, fatigue, or unexplained weight changes. It can also be part of evaluating conditions such as mitochondrial disorders, carnitine deficiency, or certain genetic disorders affecting metabolism.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if instructed by your provider. Bring any medications you’re currently taking to your appointment.
How the Test Is Performed
A blood sample is drawn from a vein in your arm. The blood is then sent to a lab for analysis using a specialized method to measure free carnitine levels.
What the Results Mean
Results may be compared to a reference range provided by your lab, but exact values can vary by lab. Low levels might suggest metabolic issues or deficiencies, while high levels could indicate certain liver or kidney problems.
Reference range
Adults: 20-50 µmol/L (free carnitine). Values vary by age; pediatric ranges are higher.N/A
No fasting required. Patient should avoid alcohol for 24 hours prior to collection. Dietary supplements containing carnitine should be noted.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Free Carnitine
Frequently asked questions
What causes low free carnitine levels?
How is free carnitine treated?
Can diet affect free 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 15, 2026. · Read our editorial policy