Serum Creatinine Phosphokinase (CPK) Activity
This test measures the activity of an enzyme called creatine phosphokinase (CPK), which helps assess muscle, heart, or brain damage.
["CPK levels can signal injury to muscles, heart tissue, or nerves."]
Key facts at a glance
- LOINC
- 48495-6
- Short code
- CDT
- Synonyms
- CDT/Tf MFr SerPl
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube; plasma acceptable in lithium heparin or EDTA tubes
- Units
- N/A
- Ref low
- 0
- Ref high
- 1.7
- Critical range
- — – 2.5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Capillary electrophoresis or HPLC (High-Performance Liquid Chromatography)
- CPT
- 82978
- SNOMED
- 440980008
- Specimen volume
- 1.0-2.0 mL of serum or plasma
- Stability
- Stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below for up to 3 months; avoid repeated freeze-thaw cycles
- Hemolysis max
- 100
- Lipemia max
- 300
- Icterus max
- 50
- TAT
- 24–72 hours
- Order
- routine
What Does CPK Measure?
Creatine phosphokinase (CPK) is an enzyme found in high concentrations in heart, skeletal muscle, and brain cells. When these tissues are damaged—due to injury, illness, or overexertion—the enzyme leaks into the bloodstream. Measuring CPK activity helps identify where and how severely damage has occurred.
Why Is This Test Important?
CPK levels can indicate conditions like heart attacks, muscle injuries (e.g., from overexertion or trauma), or neurological issues. High levels may prompt further evaluation for underlying causes.
Common Uses of CPK Testing
Doctors may order CPK tests to diagnose or monitor conditions such as myocardial infarction (heart attack), rhabdomyolysis (muscle breakdown), or stroke. It can also help track recovery after injury or surgery.
What to Expect Before or After the Test
No special preparation is needed. A blood sample is drawn from a vein, typically in your arm. Results may take a few days to a week to process, depending on your lab.
Reference range
CDT (Carbohydrate-Deficient Transferrin) ratio <1.7% is generally considered normal; values 1.7-2.0% may be borderline; values >2.0% suggest chronic alcohol consumption. Reference ranges vary by methodology.N/A
No fasting required. Patient should abstain from alcohol for at least 2 weeks prior to testing for accurate baseline assessment, as recent alcohol intake can elevate CDT levels.
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?
Can CPK Levels Change Without a Serious Condition?
How Long Do CPK Levels Stay Elevated After Injury?
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