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 if tissues are damaged.
["CPK helps identify muscle or heart damage by measuring enzyme release into the bloodstream."]
Key facts at a glance
- LOINC
- 103339-8
- Short code
- XR Toe 4th-L GE 2V
- Synonyms
- XR Toe 4th-L GE 2V
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 20
- Ref high
- 400
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- xr
- CPT
- 82670
- 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, is an enzyme found in high amounts in heart, skeletal muscle, and brain cells. When these tissues are injured or damaged, CPK leaks into the bloodstream, raising its levels. This test helps doctors evaluate conditions like heart attacks, muscle injuries, or neurological disorders.
Why Might You Need This Test?
Your doctor may order a CPK test if you have symptoms like chest pain, muscle weakness, confusion, or unexplained fatigue. It’s also used to monitor conditions like heart disease, stroke, or muscle disorders.
Common Conditions Monitored
High CPK levels may signal muscle damage (e.g., from exercise, injury, or myopathies), heart damage (e.g., during a heart attack), or neurological issues (e.g., stroke). Low levels may indicate muscle wasting or certain metabolic disorders.
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 enzymatic method. Results are typically available within 24–48 hours.
Reference range
Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: CPK Levels Reflect Tissue Damage
Short name
CPK (Serum)
Frequently asked questions
What Are Normal CPK Levels?
How Long Does It Take to Get Results?
Can CPK Levels Change with Diet or Exercise?
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