Understanding Your Diagnostic Medical Test: A Complete Patient Guide
This test measures the level of acetylcarnitine in a blood sample to evaluate metabolic function and detect certain inherited disorders.
{"Acetylcarnitine (C2) is a molecule that helps transport fatty acids for energy production","This test is commonly used in newborn screening to detect metabolic disorders","Abnormal levels may indicate problems with fatty acid metabolism or carnitine deficiency","The test is typically performed on a dried blood spot sample","Early detection of metabolic disorders allows for timely treatment and management"}
Key facts at a glance
- LOINC
- 50157-7
- Short code
- AC C2 DBS
- Synonyms
- Acetylcarn DBS-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Dried blood spot (DBS) filter paper collection card (e.g., Whatman 903 or equivalent)
- Units
- N/A
- Ref low
- 2
- Ref high
- 15
- Critical range
- 1 N/A – 25 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Tandem Mass Spectrometry (MS/MS)
- CPT
- 82017
- SNOMED
- 122269009
- Specimen volume
- 3-4 complete circles filled with blood (approximately 75-100 μL total blood)
- Stability
- Room temperature (15-25°C): 7-14 days; Refrigerated (2-8°C): 30 days; Frozen (-20°C or below): >30 days; Protect from heat and humidity
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
This test is a diagnostic procedure that helps your healthcare provider gather important information about how your body is functioning, so that a clearer picture of your overall health can be developed and shared with you.
The acetylcarnitine (C2) test measures the amount of acetylcarnitine in your blood. Acetylcarnitine is a specialized form of carnitine, a molecule that plays a crucial role in energy production. Specifically, acetylcarnitine helps transport fatty acids into the mitochondria (the energy-producing centers of cells) where they are burned for fuel. This test is often performed using a dried blood spot (DBS) sample, where a few drops of blood are collected on a special filter paper and allowed to dry.
Your doctor may order this test to help diagnose a new medical condition, monitor a health problem you already have, screen for early signs of disease before symptoms appear, or guide decisions about the treatment plan that is right for you.
The acetylcarnitine test is primarily used for: 1) Newborn screening to identify inherited metabolic disorders early, 2) Diagnosing fatty acid oxidation disorders that affect how the body converts fat into energy, 3) Evaluating carnitine deficiency or transport problems, and 4) Monitoring patients with known metabolic conditions. It is especially important for infants because metabolic disorders may not be apparent at birth but can cause serious health problems if not detected and treated early.
Your results will show whether your values fall within the normal reference range established for this test. Results within the normal range usually suggest no evidence of the condition being checked, while abnormal results may point to a health issue that needs further evaluation, repeat testing, or follow-up with your provider.
Normal acetylcarnitine levels vary by age. Elevated levels may indicate certain metabolic disorders such as medium-chain acyl-CoA dehydrogenase deficiency (MCAD), carnitine transport defects, or other fatty acid oxidation disorders. Low levels are less common but may suggest nutritional deficiencies or certain liver conditions. Your healthcare provider will interpret your results based on your age, symptoms, and other test findings.
Reference range
Reference range for Acetylcarnitine (C2) in dried blood spot: 2.0-15.0 μmol/L (typical newborn screening range); optimal: 5.0-10.0 μmol/LN/A
No fasting required; for newborn screening, specimen should be collected 24-72 hours after birth or prior to discharge; ensure proper heel stick technique for adequate blood volume
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The acetylcarnitine test is clinically significant for detecting inborn errors of metabolism, particularly fatty acid oxidation disorders. These genetic conditions prevent the body from properly breaking down fats for energy, which can lead to serious complications during periods of fasting or illness. Early detection through newborn screening allows for dietary modifications and avoidance of triggers that could cause metabolic crises. The test is also valuable for diagnosing secondary carnitine deficiency, which can occur due to certain medications, kidney dialysis, or gastrointestinal disorders that affect nutrient absorption.
Frequently asked questions
Is fasting required before this test?
How is the blood sample collected?
What happens if my baby's test is abnormal?
Are there risks associated with this test?
Sources
- 1
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- 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