Complete Blood Count (CBC) Test
This test measures the ratio of acylcarnitine to free carnitine in your blood to help diagnose metabolic disorders.
{"Measures fatty acid metabolism function","Helps detect inherited metabolic diseases","Uses a blood sample from your arm","Results help doctors diagnose conditions like fatty acid oxidation disorders","Often part of newborn screening programs"}
Key facts at a glance
- LOINC
- 59254-3
- Short code
- ACRatio
- Synonyms
- Acylcarnitine/Acyl+C0 SerPl-sRto
- Category
- chemistry
- Sample
- serum
- Container
- Serum Separator Tube (SST) or Lithium Heparin Plasma Tube
- Units
- N/A
- Ref low
- 0.05
- Ref high
- 0.2
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Tandem Mass Spectrometry (MS/MS)
- CPT
- 82017
- SNOMED
- 313295004
- Specimen volume
- 1.0 mL of serum or plasma (minimum 0.5 mL)
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 100
- Icterus max
- 20
- TAT
- 48–72 hours
- Order
- routine
A complete blood count (CBC) is a common blood test that measures the different cells in your blood, including red blood cells, white blood cells, and platelets, to give your doctor a picture of your overall health.
The acylcarnitine/carnitine free (C0) ratio test measures the amount of acylcarnitine and free carnitine in your blood and calculates their ratio. Carnitine is a substance that helps your body turn fat into energy. Acylcarnitine is produced when your body breaks down fatty acids for energy. This test helps doctors see how well your body is processing fats.
You may need this test as part of a routine checkup, to look into symptoms such as fatigue, weakness, fever, or unusual bruising, or to monitor a condition you already have or how a treatment is working.
Your doctor may order this test if they suspect a metabolic disorder, especially in newborns during routine screening. It helps detect conditions where the body cannot properly break down fatty acids for energy. Symptoms that might prompt this test include muscle weakness, low blood sugar, heart problems, or developmental delays.
The test is done with a simple blood draw. A healthcare provider will clean a spot on your arm, place a small needle into a vein, and collect a small sample of blood, which usually takes only a few minutes.
A healthcare professional will draw a small blood sample from a vein in your arm (or from your baby's heel for newborns). The blood is then sent to a laboratory where specialists measure the levels of acylcarnitine and free carnitine. The test is often done as part of a broader metabolic screening panel.
Your results show whether your blood cell counts fall within normal ranges. Abnormal levels may point to conditions such as anemia, infection, inflammation, or clotting problems, and your doctor will explain what they mean for you.
Abnormal ratios may indicate metabolic disorders such as: Primary carnitine deficiency, Multiple acyl-CoA dehydrogenase deficiency (MADD), Medium-chain acyl-CoA dehydrogenase deficiency (MCAD), or other fatty acid oxidation disorders. Your doctor will interpret the results based on your individual situation and may recommend additional tests if needed.
Reference range
The reference range for Free Carnitine (C0) ratio is typically 0.05-0.20 (acylcarnitine/total carnitine). Reference ranges may vary by laboratory and methodology.N/A
No special preparation required. Fasting is not mandatory but may be requested depending on clinical indication. Inform the patient that this test assesses carnitine metabolism and fatty acid oxidation capacity.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is primarily used for screening and diagnosing inherited metabolic disorders, particularly fatty acid oxidation disorders. These conditions occur when the body cannot properly convert fats into energy, which can lead to serious health problems if not treated early. Early detection through newborn screening allows for prompt treatment that can prevent complications and improve outcomes.
Frequently asked questions
Is fasting required before the test?
Are there any risks with this test?
What happens if the results are abnormal?
How long does it take to get results?
Sources
- 1
- 2
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 14, 2026. · Read our editorial policy