Serum Creatinine Phosphokinase (CPK) Activity
This test measures the activity of an enzyme called creatine phosphokinase (CPK), which helps assess muscle, heart, and brain health. CPK levels can rise when tissues are damaged.
["CPK helps detect muscle or heart damage by measuring enzyme levels in your blood."]
Key facts at a glance
- LOINC
- 38522-9
- Short code
- C4BP
- Synonyms
- C4b BP Act/Nor SerPl
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Enzyme-Linked Immunosorbent Assay (ELISA)
- CPT
- 86160
- SNOMED
- 12101000119109
- Specimen volume
- 1-2 mL of serum
- Stability
- Serum stable for 24 hours at room temperature; up to 7 days at 2-8°C; up to 3 months at -20°C or below for longer storage
- Hemolysis max
- 100
- Lipemia max
- 50
- Icterus max
- 25
- TAT
- 48–120 hours
- Order
- routine
What Is Creatine Phosphokinase (CPK)?
Creatine phosphokinase (CPK), also called creatine kinase, is an enzyme found in heart, skeletal, and brain cells. When these tissues are injured or stressed, CPK leaks into the bloodstream, raising its levels. This test measures how much CPK is present in your serum, helping doctors identify potential damage to these organs.
Why Might You Need This Test?
Your doctor may order a CPK test if you have symptoms like muscle weakness, chest pain, or unexplained fatigue. It’s also used to monitor conditions like heart attacks, muscle disorders, or neurological issues. CPK can help track how well treatment is working or if further intervention is needed.
Common Reasons for Testing
Common reasons include diagnosing conditions like heart attacks (myocardial infarction), muscle injuries, or neurological disorders. It may also be used to check for complications from medications, infections, or metabolic disorders.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to avoid strenuous exercise or certain medications for 24 hours before testing. If you’re taking blood thinners or muscle relaxants, let your doctor know.
Reference range
Reference ranges vary by laboratory and assay methodology; consult local laboratory reference values.N/A
No special patient preparation required. Specimen collection should follow standard venipuncture procedures.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CPK Serum
Frequently asked questions
What Are Normal CPK Levels?
How Do CPK Levels Change with Illness?
Can CPK Levels Be Used to Monitor Treatment?
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 15, 2026. · Read our editorial policy