Skip to content

Understanding This Test: What It Is, Why It Matters, and What to Expect

Published: August 9, 2026Updated: August 10, 2026

This test measures the levels of free carnitine (C0) and acylcarnitines in your blood to evaluate how your body processes fats for energy.

Quick summary

{"Measures free carnitine (C0) and acylcarnitine levels in blood","Helps diagnose metabolic disorders affecting fat burning","Used to monitor certain medication effects","Sample is collected from a vein in your arm","Results help doctors assess energy metabolism function"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 10, 2026Editorial policy

Key facts at a glance

LOINC
30193-7
Short code
C0
Synonyms
Acylcarnitine/C0 SerPl-sRto
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or lithium heparin plasma tube
Units
N/A
Ref low
25
Ref high
60
Critical range
10 N/A – 100 N/A
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
Tandem Mass Spectrometry (MS/MS)
CPT
81401
SNOMED
104435004
Specimen volume
1.0-2.0 mL serum or plasma minimum
Stability
Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days
Hemolysis max
50
Lipemia max
300
Icterus max
20
TAT
48–120 hours
Order
routine

What is this test and why might my healthcare provider recommend it?

The acylcarnitine/carnitine (C0) test measures the amounts of free carnitine and various acylcarnitines in your blood serum or plasma. Carnitine is a substance that helps your body convert fats into energy. This test evaluates how well your body is using fat for energy and can detect problems with fat metabolism.

Why is this test important for my overall health and ongoing medical care?

Carnitine plays a crucial role in energy production by transporting fatty acids into mitochondria, the powerhouses of cells. The test can identify disorders where the body cannot properly use fats for energy, which can cause serious health problems if left untreated.

How is this test performed, and what should I expect during the procedure?

A healthcare professional will draw a small blood sample from a vein in your arm. The sample is then sent to a laboratory where specialists measure the levels of free carnitine (C0) and different acylcarnitine compounds. The results are often reported as molar ratios to help identify specific metabolic patterns.

What do the results mean, and how will my doctor explain them to me?

Abnormal levels of carnitine and acylcarnitines may indicate various metabolic conditions. Your doctor will interpret the results based on your symptoms, medical history, and other test results. The pattern of different acylcarnitines can help identify specific metabolic disorders.

Reference range

Reference range varies by age and laboratory; typically 25-60 μmol/L for adultsN/A

Specimen: serum

No special preparation required. Patient does not need to fast. Inform clinician of any supplements or medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test helps diagnose and monitor conditions related to carnitine deficiency or abnormal fatty acid metabolism, including primary carnitine transporter deficiency, various organic acidemias, and fatty acid oxidation disorders. It is also used to monitor patients taking certain medications that can affect carnitine levels, such as valproic acid, isoniazid, or certain chemotherapy drugs.

Frequently asked questions

Do I need to fast before this test?
Your doctor may ask you to fast for a certain period before the test, typically 8-12 hours. Follow your healthcare provider's specific instructions.
Is the test painful?
You may feel a brief pinch or mild discomfort when the blood is drawn, but the pain is usually minimal and short-lived.
How long does it take to get results?
Results typically take a few days to a week, as this test requires specialized laboratory analysis.
What happens if my results are abnormal?
Abnormal results do not always mean you have a serious condition. Your doctor will discuss your results with you and may recommend additional tests or refer you to a specialist for further evaluation.
Can medications affect my test results?
Yes, certain medications can affect carnitine levels. Tell your doctor about all medications, supplements, and vitamins you are taking before the test.
  1. 1
    MedlinePlus - CarnitineSource
  2. 2
    Mayo Clinic Laboratories - Acylcarnitine ProfileSource

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.

Medical Disclaimer

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