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Serum Creatinine Phosphokinase (CPK) Activity

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

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.

Quick summary

["CPK helps identify muscle injuries, heart strain, or neurological conditions."]

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

Key facts at a glance

LOINC
15476-5
Short code
L inter Brat Ab Titr Ser Aggl
Synonyms
L inter Brat Ab Titr Ser Aggl
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
aggl
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 found in heart, brain, and skeletal muscle cells. When these tissues are damaged—due to injury, illness, or overexertion—the enzyme leaks into the bloodstream, raising CPK levels. This test measures how much CPK is present in your serum.

Why Might You Need This Test?

Doctors order CPK tests to diagnose or monitor conditions affecting muscle, heart, or brain function. Common reasons include suspected muscle injuries (e.g., from exercise, trauma), heart problems (e.g., heart attack), or neurological disorders (e.g., stroke). It may also be used to evaluate symptoms like muscle weakness, pain, or fatigue.

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 hours.

What Do Results Mean?

Elevated CPK levels may indicate recent muscle damage, heart issues, or other conditions. However, normal results don’t rule out all possible causes. 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.

Clinical Significance

Short name

CPK (Serum)

Frequently asked questions

Could elevated CPK levels cause long-term harm?
Elevated CPK alone often resolves once the underlying cause (e.g., muscle injury or temporary stress) improves. However, persistent high levels may signal chronic conditions like muscle disorders or heart disease. Always discuss results with your doctor.
What if my CPK is very high?
Very high CPK may signal severe muscle damage (e.g., from a heart attack, stroke, or severe illness). Your doctor will investigate further with additional tests or questions about recent activities or symptoms.
Do I need to prepare for this test?
No special preparation is needed. Avoid strenuous exercise 24 hours before the test, as it may temporarily raise CPK levels.
  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