Understanding This Medical Test: What It Is, Why You May Need It, How to Prepare, and What Your Results Mean
A blood test that measures the level of acetylcarnitine, a molecule important for energy metabolism, to help diagnose metabolic disorders.
{"Acetylcarnitine helps your body convert fat into energy","The test helps diagnose carnitine deficiency and fatty acid oxidation disorders","Results are often part of a broader metabolic screening panel"}
Key facts at a glance
- LOINC
- 30191-1
- Short code
- C2
- Synonyms
- Acetylcarn SerPl-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or plain red top tube. Avoid gel tubes if possible for mass spectrometry analysis.
- Units
- N/A
- Ref low
- 5
- Ref high
- 15
- Critical range
- 2 N/A – 50 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Tandem Mass Spectrometry (LC-MS/MS)
- CPT
- 82017
- SNOMED
- 313336005
- Specimen volume
- 1.0 mL minimum, 2.0 mL preferred
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Protect from light.
- Hemolysis max
- 50
- Lipemia max
- 100
- Icterus max
- 20
- TAT
- 48–96 hours
- Order
- routine
What is this test, and what is it designed to find, measure, or rule out as part of my overall medical care?
The acetylcarnitine (C2) test measures the amount of acetylcarnitine in your blood. Acetylcarnitine is a specialized molecule derived from L-carnitine that plays a vital role in energy production. It helps transport fatty acids into the mitochondria (the energy-producing centers of cells) where they are burned for fuel. This test is typically performed on a blood sample (serum or plasma) and is part of a comprehensive metabolic evaluation.
Why might I need this test, and what symptoms or health concerns could make my doctor recommend it for me?
Your doctor may order this test if they suspect a problem with your body's ability to metabolize fats for energy. Common reasons include: evaluating symptoms like muscle weakness, fatigue, or heart problems; screening for inherited metabolic disorders; monitoring treatment with L-carnitine supplements; or investigating abnormal results from other metabolic tests. It is often part of a newborn screening panel or a more comprehensive carnitine profile test.
How should I prepare for the test, and are there special instructions about food, drink, or my medicines?
Preparation may vary based on your specific situation. Fasting for 8-12 hours is often recommended as acetylcarnitine levels can be affected by recent food intake. Your doctor will provide specific instructions. Be sure to inform your healthcare provider about any medications or supplements you are taking, especially L-carnitine or acetyl-L-carnitine supplements, as these can affect test results.
What do the results of this test mean, and how will my doctor use them to guide my treatment and follow-up care?
Results are reported as concentrations in the blood. Low levels may indicate carnitine deficiency, which can cause muscle weakness, heart problems, and fatigue. Elevated levels may suggest certain metabolic disorders, including fatty acid oxidation disorders or specific genetic conditions. Your doctor will interpret your results in the context of your symptoms, medical history, and other test findings.
Reference range
Reference range: 5.0-15.0 μmol/L. Ranges may vary by laboratory and population. Pediatric and neonatal reference ranges differ significantly.N/A
No fasting required. Avoid fatty meals 24 hours prior to collection if possible, as this may temporarily elevate acylcarnitine levels. Inform laboratory of any medications or supplements, especially L-carnitine supplementation.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is primarily used to evaluate disorders of carnitine metabolism and fatty acid oxidation. Abnormal results may indicate primary carnitine deficiency (a genetic disorder where the body cannot properly transport carnitine), secondary carnitine deficiency (due to other conditions like kidney disease or certain medications), or inborn errors of metabolism affecting fatty acid oxidation. The test is valuable for diagnosing conditions such as carnitine palmitoyltransferase (CPT) deficiencies and multiple acyl-CoA dehydrogenase deficiency (MADD). Early detection through newborn screening or diagnostic testing allows for timely treatment, which can significantly improve outcomes.
Frequently asked questions
Is this test painful?
How long does it take to get results?
Do I need to fast before this test?
What happens if my results are abnormal?
Sources
- 1
- 2
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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