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Serum Creatinine Phosphokinase (CPK) Activity (Mass Concentration)

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

This test measures the activity level of Creatine Phosphokinase (CPK), an enzyme found in heart, skeletal, and smooth muscle cells. It helps assess muscle damage or heart-related conditions.

Quick summary

["CPK levels can indicate 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
13225-8
Short code
CMV IgG sp1 SerPl-aCnc
Synonyms
CMV IgG sp1 SerPl-aCnc
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 Does CPK Measure?

Creatine Phosphokinase (CPK), also known as Creatine Kinase (CK), is an enzyme that plays a role in energy production within cells. When muscle or heart tissue is damaged, CPK leaks into the bloodstream, raising its levels. This test specifically measures the activity of CPK in your serum, which can help identify sources of injury.

Why Is This Test Done?

Doctors may order a CPK test to evaluate symptoms such as chest pain, muscle weakness, or unexplained fatigue. It is also used to monitor conditions like heart attacks, muscle disorders, or neurological issues that may cause muscle damage.

Common Uses and Conditions

Common reasons for testing include diagnosing conditions like myocardial infarction (heart attack), muscle injuries, or neurological disorders. Elevated CPK levels may suggest recent trauma, exercise-induced muscle damage, or underlying health issues requiring further investigation.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to avoid strenuous exercise or certain medications that could affect results. If you have a history of muscle damage or heart conditions, inform your healthcare provider before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CPK Serum

Frequently asked questions

What are elevated CPK levels?
Elevated CPK levels often indicate recent muscle or heart damage. For example, high levels can be seen after a heart attack, muscle strain, or conditions like myositis. However, CPK levels alone are not definitive and may require additional testing for diagnosis.
What are normal CPK levels?
Normal CPK levels vary by individual and can be influenced by factors like age, sex, and overall health. Your healthcare provider will interpret results in the context of your medical history and symptoms.
How long does it take to get results?
Results are typically available within 24 to 48 hours, depending on the lab and your healthcare provider’s protocol. Follow-up instructions from your doctor will guide next steps based on your test results.
  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