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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, skeletal, and smooth muscle cells. It helps assess muscle damage or heart-related conditions.

Quick summary

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

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

Key facts at a glance

LOINC
13220-9
Short code
C trach C IgM Ser-aCnc
Synonyms
C trach C IgM Ser-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 Is Creatine Phosphokinase (CPK)?

Creatine phosphokinase (CPK), also called creatine kinase, is an enzyme that plays a role in energy production in cells. It exists in different forms (isoenzymes) in the body, with the total CPK test measuring all forms combined. This enzyme is released into the bloodstream when muscle or heart tissue is damaged, making it useful for detecting conditions like heart attacks, muscle injuries, or other illnesses affecting these tissues.

Why Might You Need This Test?

Your healthcare provider may order a total CPK test to investigate symptoms such as chest pain, muscle weakness, or unexplained fatigue. It can also help diagnose conditions like myocarditis (heart inflammation), rhabdomyolysis (severe muscle breakdown), or evaluate muscle disorders.

When Might Results Be Abnormal?

Elevated CPK levels may indicate recent muscle injury, heart damage, or certain metabolic disorders. However, normal results do not guarantee no damage has occurred—results should always be interpreted by a healthcare professional in the context of your symptoms and medical history.

What Could Affect Results?

Factors that may influence CPK levels include recent exercise, muscle trauma, certain medications (like statins), or underlying conditions like thyroid disorders. Avoid strenuous activity 24–48 hours before testing to get the most accurate results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Total CPK

Frequently asked questions

Could CPK levels be affected by pregnancy?
Yes, CPK levels can be influenced by pregnancy due to hormonal changes and increased muscle activity. However, pregnancy alone typically does not cause abnormal CPK results unless there is an underlying muscle or heart condition.
What does a very high CPK level mean?
Very high CPK levels often signal severe muscle damage (e.g., from a heart attack, severe injury, or conditions like rhabdomyolysis). Your doctor will review the results alongside your symptoms and other tests to determine the cause.
Do CPK levels change with age?
Yes, CPK levels can vary with age. Older adults may have slightly lower baseline levels, but age alone does not cause abnormal results unless there is an underlying health issue affecting muscle or heart function.
  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