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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 when tissues are damaged.

Quick summary

["CPK helps identify muscle, heart, or brain injuries by detecting enzyme leaks from affected cells."]

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

Key facts at a glance

LOINC
7453-4
Short code
Ltx Greer BasoBnd Ab Qn
Synonyms
Ltx Greer BasoBnd Ab Qn
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
lhr
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Is Creatine Phosphokinase (CPK)?

Creatine phosphokinase (CPK), also called creatine kinase (CK), is an enzyme found in high concentrations in heart, skeletal muscle, and brain cells. When these tissues are damaged—due to injury, illness, or overuse—the enzyme leaks into the bloodstream, raising CPK levels. This test measures how much CPK is present in your serum.

Why Is CPK Tested?

Doctors may order a CPK test to investigate symptoms like muscle weakness, chest pain, or neurological issues. Elevated CPK can signal conditions such as heart attacks, muscle injuries (e.g., from overexertion or trauma), or certain neurological disorders.

When Might You Need This Test?

You might need a CPK test if you have unexplained muscle pain, fatigue, or symptoms like shortness of breath, dizziness, or confusion. It’s also used as part of a broader evaluation for conditions like heart attacks, stroke, or muscle disorders.

How Is the Test Performed?

A blood sample is drawn 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.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CPK Serum

Frequently asked questions

What Does a High CPK Level Mean?
Elevated CPK levels can indicate tissue damage in muscles, the heart, or brain. Common causes include muscle injuries (e.g., from exercise or trauma), heart attacks, or conditions like myopathy (muscle diseases). However, CPK alone isn’t diagnostic—your doctor will consider symptoms and other test results.
What Does a Low CPK Level Mean?
Low CPK levels are less common but may occur in certain genetic disorders, severe muscle wasting, or if your body isn’t producing enough CPK. They’re usually not a cause for concern unless combined with other symptoms.
How Often Should I Get This Test?
Your doctor will determine how often you need CPK testing based on your health history, symptoms, and other tests. Regular monitoring may be recommended if you have a history of muscle disorders, heart disease, or conditions like myasthenia gravis.
  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