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Serum Creatinine Phosphokinase (CPK) Activity

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

This test measures the activity of creatine phosphokinase, an enzyme found in heart, skeletal, and smooth muscle tissues. It helps assess muscle damage or conditions affecting these tissues.

Quick summary

["CPK helps identify muscle injuries or diseases by measuring enzyme release into the bloodstream."]

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

Key facts at a glance

LOINC
10480-2
Short code
ERA+PGRA Ag Tiss Ql ImStn
Synonyms
ERA+PGRA Ag Tiss Ql ImStn
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
immune-stain
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 CPK Used For?

CPK levels can indicate muscle injury, such as from overexertion, trauma, or conditions like myositis (inflammation of muscles). It may also be checked after heart attacks or other cardiac events to monitor muscle damage.

Why Might CPK Be Ordered?

Your doctor may order CPK if you have symptoms like muscle pain, weakness, or swelling, or if you’ve experienced recent trauma, surgery, or a heart-related event.

How Is CPK Tested?

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.

What Are Common Causes of Elevated CPK?

High CPK levels can result from muscle damage (e.g., from exercise, injury, or conditions like rhabdomyolysis), heart problems, or certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CPK is clinically significant because elevated levels often signal muscle injury or disease, guiding treatment for conditions like myopathies, heart attacks, or toxic exposures. However, it’s not specific to any single condition and may require additional testing for diagnosis.

Short name

CPK (Serum)

Frequently asked questions

What does a high CPK level mean?
A high CPK level suggests possible muscle damage or disease, but your doctor will consider your symptoms, medical history, and other test results to determine the cause.
How long does it take to get CPK results?
Results are typically available within 24 to 48 hours, depending on your lab’s processing time.
Can CPK levels be affected by diet or exercise?
Exercise can temporarily raise CPK levels, but diet alone usually does not significantly affect it unless you have muscle-related conditions like myositis.
  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