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Serum Creatinine Phosphokinase (CPK) Activity

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

This test measures the activity of Creatine Phosphokinase (CPK), an enzyme found in heart, skeletal muscle, and brain tissues. It helps assess muscle damage, heart function, or neurological conditions.

Quick summary

["CPK helps identify muscle or heart injury by detecting enzyme release into the bloodstream."]

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

Key facts at a glance

LOINC
52758-0
Short code
SERPINE1 c.-844A>G Bld/T Ql
Synonyms
SERPINE1 c.-844A>G Bld/T Ql
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
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)?

CPK, or Creatine Phosphokinase, is an enzyme that plays a role in energy production in cells. When muscle or heart tissue is damaged, CPK leaks into the bloodstream, where it can be measured. This test is often used to detect conditions like heart attacks, muscle injuries, or neurological disorders.

Why Might You Need This Test?

Your doctor may order a CPK test if you have symptoms like chest pain, muscle weakness, or unexplained fatigue. It can also be part of routine monitoring for certain conditions, such as heart disease or muscle disorders.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab for analysis. The test measures CPK levels in your serum (liquid part of blood).

What Are Common Causes of Abnormal Results?

Elevated CPK levels may indicate muscle damage (e.g., from exercise, injury, or conditions like myositis), heart problems (e.g., heart attack), or neurological issues. Low levels may suggest muscle wasting or certain metabolic disorders.

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?
A high CPK level may suggest recent muscle injury, heart damage, or other conditions causing tissue breakdown. Your doctor will review your symptoms and other test results to determine the cause.
What does a low CPK level mean?
Low CPK levels might indicate muscle atrophy, certain metabolic disorders, or conditions affecting muscle function. Further testing or evaluation may be needed to understand the reason.
Can CPK levels change with diet or exercise?
Yes, CPK levels can rise temporarily after intense physical activity or muscle strain. However, chronic elevation may require medical attention to rule out underlying conditions.
  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