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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 areas.

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
103237-4
Short code
XR Toes-L GE 2V
Synonyms
XR Toes-L GE 2V
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
20
Ref high
400
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr
CPT
82670
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 disorders.

How Is CPK Tested?

A blood sample is drawn, and the enzyme activity is measured using an immunoassay or enzymatic method. Results are compared to a reference range based on your health and lab standards.

When Might You Need This Test?

Your doctor may order CPK if you experience chest pain, muscle weakness, unexplained fatigue, or symptoms of a heart attack, stroke, or severe muscle injury.

What Could Affect Results?

Factors like recent exercise, muscle trauma, certain medications, or underlying conditions (e.g., kidney disease) can influence CPK levels. Avoid strenuous activity 24 hours before testing.

Reference range

Premenopausal: 20-400 pg/mL; Postmenopausal: <30 pg/mLN/A

Specimen: serum

No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CPK (Serum)

Frequently asked questions

Why was my CPK test ordered?
Your doctor may have suspected muscle or heart damage based on symptoms like pain, weakness, or lab findings. CPK helps confirm or rule out conditions like a heart attack or muscle injury.
What do my CPK results mean?
Results alone don’t diagnose a condition—they’re part of a bigger picture. Your doctor will discuss them with your full medical history and other test results. Ask for clarification if needed.
Can I lower my CPK levels naturally?
While CPK levels are influenced by tissue damage, lifestyle changes like reducing alcohol, avoiding extreme exercise, and managing chronic conditions (e.g., diabetes) may support overall health but won’t directly lower CPK.
  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