Serum Creatinine Phosphokinase (CPK) Activity
This test measures the activity level of Creatine Phosphokinase (CPK), an enzyme found in heart, skeletal, and smooth muscle cells. It helps assess muscle damage or heart strain.
["CPK levels can signal muscle injury or heart-related issues."]
Key facts at a glance
- LOINC
- 28657-5
- Short code
- Fact Xa Act/Nor PPP Chro
- Synonyms
- Fact Xa Act/Nor PPP Chro
- Category
- chemistry
- Sample
- plasma
- Container
- Lavender-top (EDTA) or Green-top (Heparin)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- chromo
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What Is Creatine Phosphokinase (CPK)?
Creatine phosphokinase (CPK), also called creatine kinase (CK), is an enzyme that helps produce energy in cells. It’s naturally present in heart, brain, skeletal muscles, and other tissues. When muscle or heart tissue is damaged, CPK leaks into the bloodstream, raising its levels. This test helps doctors identify conditions like muscle injuries, heart attacks, or other muscle-related problems.
Why Might You Need This Test?
Your doctor may order a CPK test if you have symptoms like muscle weakness, pain, or fatigue, or if you’re experiencing chest pain or shortness of breath. It’s also used to monitor conditions like myopathy (muscle disorders), heart disease, or after certain surgeries or injuries.
How Is the Test Performed?
A blood sample is taken from a vein in your arm. The sample is sent to a lab, where CPK activity is measured using an immunoassay or enzymatic method. Results are typically available within 24 to 48 hours.
What Do the Results Mean?
CPK levels vary depending on factors like age, sex, and overall health. Elevated levels may indicate muscle damage, heart problems, or other conditions. Your doctor will interpret results in the context of your symptoms and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
CPK is a key marker for diagnosing and monitoring muscle and heart conditions. High levels can signal acute muscle injury (e.g., from overexertion, trauma, or certain medications), heart attacks, or chronic muscle diseases. Low levels may raise concerns about muscle wasting or certain metabolic disorders, though this is less common. Regular monitoring of CPK can help track the progression or response to treatment in patients with known muscle or heart conditions.
Short name
CPK Serum
Frequently asked questions
What causes elevated CPK levels?
What causes low CPK levels?
How often should I get this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 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