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Carnitine Palmitoyltransferase II Activity (Serum)

Published: August 9, 2026Updated: August 16, 2026

This test measures the activity of the enzyme carnitine palmitoyltransferase II (CPT-II) in your blood. It helps assess how well your muscles and other tissues can use fat for energy.

Quick summary

["This test may help diagnose or monitor conditions affecting fat metabolism in muscles."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
55854-4
Short code
Dicarboxydodecanoylcarn Amn-sCnc
Synonyms
Dicarboxydodecanoylcarn Amn-sCnc
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

What This Test Measures

CPT-II is a critical enzyme in the process of transporting long-chain fatty acids into mitochondria for energy production. Low activity levels may indicate impaired fat metabolism, often linked to genetic disorders like mitochondrial disorders or muscle disorders.

Why It’s Ordered

Your healthcare provider may order this test if you have symptoms such as muscle weakness, exercise intolerance, or unexplained fatigue, especially if these symptoms occur after eating a high-fat meal. It’s also used in the evaluation of suspected metabolic or mitochondrial disorders.

Common Conditions Monitored

Conditions like CPT-II deficiency (a genetic disorder) or other mitochondrial disorders may affect how your body breaks down fats for energy. This test helps confirm or rule out these conditions by checking enzyme function.

Sample Collection and Preparation

A blood sample is drawn from a vein in your arm. The sample is collected in a special tube to separate serum (the liquid part of blood without clots). The serum is then sent to a lab for testing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Carnitine palmitoyltransferase II (CPT-II) deficiency can cause severe muscle weakness, especially during exercise or after consuming fatty foods. Early diagnosis and management can improve quality of life and prevent complications.

Short name

CPT-II Activity

Frequently asked questions

Why might my doctor recommend this test?
Your doctor may recommend this test if you have symptoms like unexplained muscle weakness, fatigue, or issues with exercise tolerance—especially if these symptoms worsen after eating fatty foods. It’s also used in genetic testing for metabolic disorders.
What does a low or high result mean?
Low enzyme activity suggests a possible CPT-II deficiency or other metabolic issues. High activity may not indicate a problem unless combined with clinical symptoms. Results are interpreted by a healthcare provider in the context of your symptoms and medical history.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on lab processing times. Your doctor will discuss the findings with you during your follow-up visit.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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 16, 2026. · Read our editorial policy