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Serum Creatinine Phosphokinase (CPK) or Creatine Kinase (CK) Activity

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

This test measures the activity of creatine kinase, an enzyme found in heart, muscle, and brain tissues. It helps assess damage to these organs.

Quick summary

["CPK/CK helps identify muscle, heart, or brain injuries by detecting elevated enzyme levels after tissue damage."]

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

Key facts at a glance

LOINC
47919-6
Short code
GH 45M p Arg+Ins SerPl-aCnc
Synonyms
GH 45M p Arg+Ins SerPl-aCnc
Category
hormone
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

Why Is This Test Done?

Your doctor may order this test to check for muscle damage (myopathy), heart problems (such as a heart attack), or nerve/brain conditions. It’s often used alongside other tests to diagnose or monitor these conditions.

What Does the Test Involve?

A blood sample is taken from a vein in your arm. The lab then measures the enzyme activity in your serum. Results are compared to a general reference range to identify abnormalities.

What Are Common Causes of Abnormal Results?

High CPK/CK levels may occur after muscle injury (e.g., from exercise, trauma, or illness), heart attacks, or certain neurological conditions. Low levels might indicate muscle wasting or rare enzyme deficiencies.

How Do Results Affect My Health?

Elevated CPK/CK can signal acute tissue damage and prompt further testing (e.g., for heart disease or rhabdomyolysis). Your doctor will interpret results in context with your symptoms and other tests.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CPK/CK Activity

Frequently asked questions

Why might my CPK/CK test be ordered if I don’t have obvious symptoms?
Your doctor may order it to monitor conditions like muscle disorders, heart disease, or to investigate unexplained weakness, fatigue, or neurological symptoms.
What should I do if my CPK/CK levels are high?
Report elevated results to your doctor immediately. They may recommend additional tests (e.g., ECG, muscle biopsy) or treatments to address the underlying cause, such as rest, medication, or lifestyle changes.
Can CPK/CK levels change with diet or exercise?
Yes, intense exercise or muscle strain can temporarily raise CPK/CK levels. However, chronic elevation may signal a need for further evaluation, especially if symptoms persist.
  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