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 levels can help diagnose or monitor conditions affecting fat metabolism or muscle function."]
Key facts at a glance
- LOINC
- 2043-8
- Short code
- C0
- Synonyms
- Carnitine Free SerPl-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube (no anticoagulant) or serum separator tube (SST)
- Units
- N/A
- Ref low
- 25
- Ref high
- 60
- Critical range
- 5 N/A – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–999 years
- Method
- Tandem Mass Spectrometry (MS/MS) or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 82379
- SNOMED
- 104687009
- 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. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 24–72 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may order a free carnitine test if you have symptoms like muscle weakness, fatigue, or unexplained high blood fats (triglycerides). It’s also used in cases of suspected inherited disorders like primary carnitine deficiency or mitochondrial disorders.
What to Expect Before the Test
No special preparation is needed, but you may be asked to fast for 8–12 hours before the draw if your test is part of a metabolic panel. Wear comfortable clothing for the blood draw.
What the Test Results Mean
Results are compared to a general reference range for healthy adults, though values can vary by lab. Low levels may indicate metabolic disorders, while very high levels could suggest muscle breakdown or certain liver conditions.
Common Conditions Monitored
This test is often used to monitor patients with inherited carnitine deficiency, muscle disorders, or those on certain medications that affect carnitine metabolism.
Reference range
Adults: 25-60 μmol/L (may vary by laboratory). Pediatric and neonatal ranges differ; consult laboratory-specific reference intervals.N/A
Fasting is not required. However, overnight fasting may be recommended for metabolic evaluation. Avoid recent carnitine supplementation before specimen collection unless specifically directed by physician.
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 long does it take to get results?
Can diet affect free carnitine test results?
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