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Serum Creatinine Phosphokinase (CPK) Activity

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

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

Quick summary

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

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

Key facts at a glance

LOINC
109932-4
Short code
GQ1b Gangl IgM Msmt Ser
Synonyms
GQ1b Gangl IgM Msmt Ser
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
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 CPK Used For?

CPK levels can indicate conditions like heart attacks, muscle injuries (e.g., from exercise or trauma), or neurological disorders. High levels may signal tissue damage, while low levels could suggest muscle wasting or certain metabolic conditions.

When Might You Need This Test?

Your doctor may order CPK if you have symptoms like chest pain, muscle weakness, or unexplained fatigue. It’s also used during monitoring for conditions like heart disease, stroke, or muscle disorders.

How Is the Test Done?

A blood sample is taken from a vein, usually in your arm. The sample is sent to a lab where the enzyme activity is measured. Results are typically available within 24–48 hours.

What Do Results Mean?

Results compare your CPK activity to a general reference range. Elevated levels may prompt further testing for underlying causes, while normal levels don’t rule out all possible conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

CPK plays a key role in diagnosing and managing conditions affecting muscle or heart function. It’s often used alongside other tests (e.g., troponin for heart attacks) to provide a fuller picture of tissue damage.

Short name

CPK (Serum)

Frequently asked questions

Why do I need this test if I don’t have symptoms?
Your doctor may recommend it as part of routine monitoring, especially if you have a history of muscle disorders, heart disease, or conditions that increase risk (e.g., high physical activity, certain medications).
What are common causes of high CPK levels?
High CPK can result from muscle injury (e.g., from exercise, trauma, or overuse), heart attacks, stroke, or neurological conditions like multiple sclerosis. Certain medications (e.g., statins) or metabolic disorders may also affect levels.
How long does it take to get results?
Results are usually ready within 24–48 hours, depending on lab processing times. Your doctor will discuss them with you during your follow-up visit.
  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