Carnitine/Long-Chain Acylcarnitine Profile (Serum)
This test measures levels of carnitine and long-chain acylcarnitines in your blood. These compounds help transport fatty acids into cells for energy production and detoxify harmful substances.
["Assesses fat metabolism and toxin clearance in your body."]
Key facts at a glance
- LOINC
- 54442-9
- Short code
- CARNRAT
- Synonyms
- Carn esters/C0 Ur-sRto
- Category
- chemistry
- Sample
- urine
- Container
- Sterile, screw-capped plastic urine collection container; transfer to sterile cryovial preferred for frozen storage
- Units
- N/A
- Ref low
- 0
- Ref high
- 2
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–99 years
- Method
- Tandem Mass Spectrometry (MS/MS) with electrospray ionization; quantifies free carnitine (C0) and total carnitine esters via precursor ion scanning, with calculation of the molar ratio of esters to free carnitine
- CPT
- 82017
- SNOMED
- 44636007
- Specimen volume
- 5-10 mL random or 24-hour urine collection; minimum 2 mL for analysis
- Stability
- Refrigerated (2-8°C): up to 24 hours; Frozen (-20°C or below): up to 30 days; Avoid repeated freeze-thaw cycles
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- 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 vomiting, especially if they suspect metabolic disorders affecting how your body uses fats. It’s also used to monitor conditions like mitochondrial disorders, inherited carnitine deficiencies, or unexplained metabolic imbalances.
What to Expect Before the Test
No special preparation is typically needed, but you may be asked to fast for 8–12 hours before the blood draw. Avoid strenuous activity on the day of the test. If you’re on medications, let your provider know beforehand.
What the Test Involves
A healthcare professional will draw blood from a vein in your arm. The sample is sent to a lab for analysis, where carnitine and acylcarnitine levels are measured using specialized techniques like mass spectrometry.
What the Results Mean
Results show the concentration of carnitine and specific acylcarnitines in your blood. Abnormal levels may indicate issues with fat metabolism, mitochondrial function, or toxin buildup. Your provider will interpret these results in the context of your symptoms and medical history.
Reference range
Normal urinary acylcarnitine ester/free carnitine (C0) molar ratio is typically <2.0 in healthy individuals. Results should be interpreted alongside plasma acylcarnitine profile and clinical findings. Values may vary by laboratory and analytical method.N/A
No special preparation required. Patients should maintain normal dietary intake prior to collection. Avoid strenuous exercise immediately before collection. For metabolic evaluation, sample collection during an acute illness episode may be diagnostically informative.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low carnitine levels or abnormal acylcarnitine patterns can signal metabolic disorders, such as primary carnitine deficiency, mitochondrial diseases, or conditions like medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. Elevated acylcarnitines may also point to toxic exposures or enzyme deficiencies affecting fat breakdown. Early detection can guide treatment, such as dietary adjustments or medication.
Short name
Carnitine Profile
Frequently asked questions
How long will it take to get my results?
What does ‘long-chain acylcarnitine’ mean?
Can I eat or drink anything 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 16, 2026. · Read our editorial policy