Carnitine Acylcarnitine Profile (Free Carnitine and Acylcarnitine Metabolites)
This test measures levels of free carnitine and various acylcarnitines in your blood, which help assess how well your body is converting fats into energy.
["Helps identify metabolic disorders linked to fat metabolism or mitochondrial function."]
Key facts at a glance
- LOINC
- 44710-2
- Short code
- CARNRAT
- Synonyms
- Carnitine/Acylcarnitine SerPl-sRto
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum separator tube (SST) or plain red-top tube; plasma collected in lithium-heparin or EDTA tube is also acceptable.
- Units
- N/A
- Ref low
- 0.25
- Critical range
- 0.1 N/A – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Tandem Mass Spectrometry (MS/MS)
- CPT
- 82017
- SNOMED
- 445980008
- Specimen volume
- 1 mL serum or plasma (minimum 0.5 mL); pediatric minimum 0.2 mL
- Stability
- Stable for 7 days at 2-8°C (refrigerated); for prolonged storage, freeze at -20°C or below for up to 3 months. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 48–168 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 health issues that could be related to carnitine metabolism. It’s also used to monitor conditions like mitochondrial disorders, fatty acid oxidation defects, or inherited metabolic diseases.
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 provider specifies it. Bring any medications you’re taking to discuss with your doctor.
How the Test Works
A blood sample is taken from a vein in your arm. The blood is then analyzed using a specialized technique (likely high-performance liquid chromatography) to measure free carnitine and different acylcarnitine compounds.
What the Results Mean
Abnormal results may indicate imbalances in fat metabolism, mitochondrial function, or genetic disorders affecting carnitine transport. Your doctor will interpret results in the context of your symptoms and medical history.
Reference range
Free carnitine/acylcarnitine ratio: >0.25 (normal); 0.10-0.25 (borderline); <0.10 (abnormal). Age- and reference-lab-specific values apply.N/A
No special preparation required. Patient should be informed that the test helps evaluate mitochondrial fatty acid oxidation and carnitine metabolism. Sample should ideally be collected at least 2 weeks after the last carnitine supplementation to obtain meaningful baseline values.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Carnitine Metabolite Panel
Frequently asked questions
What could cause abnormal results?
How might my doctor use these results?
Do I need to do anything special after 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 10, 2026. · Read our editorial policy