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Serum Creatinine Phosphokinase (CPK) Isoenzyme Assay (Total CPK)

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

This test measures the total activity of Creatine Phosphokinase (CPK), an enzyme found in heart, muscle, and brain tissues. It helps assess damage to these organs.

Quick summary

["CPK levels can signal muscle or heart injury and guide treatment decisions."]

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

Key facts at a glance

LOINC
60645-9
Short code
Sn-Li Skull XR
Synonyms
Sn-Li Skull XR
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-measured
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 that helps convert creatine and ATP into energy in cells. It exists in different forms (isoenzymes) in the body, with the total CPK test combining all forms. Elevated levels often appear when cells are damaged, such as in heart attacks, muscle injuries, or neurological conditions.

Why Might This Test Be Ordered?

Your doctor may order a total CPK test to investigate symptoms like chest pain, muscle weakness, or neurological issues. It’s also used after trauma, surgery, or exercise to check for tissue damage.

Common Causes of Elevated CPK Levels

High CPK levels can result from muscle injuries (e.g., cramps, strains), heart attacks, stroke, or certain medications. Low levels may suggest muscle wasting or certain metabolic 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 using an immunoassay method to measure CPK activity.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Total CPK

Frequently asked questions

How long does it take to get results from this test?
Results typically arrive within 24 to 48 hours, depending on lab processing times. Your doctor will discuss them during your follow-up visit.
Can CPK levels be affected by diet or exercise?
Yes, intense physical activity or muscle strain can temporarily raise CPK levels. Avoiding strenuous exercise 24–48 hours before testing helps ensure accurate results.
What are the normal ranges for CPK?
Normal ranges vary by lab and age. Your doctor will compare your results to your specific reference values and clinical context.
  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