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Serum or Plasma Creatinine Phosphokinase (CPK) Activity

Published: August 9, 2026Updated: August 17, 2026

This test measures the activity of an enzyme called creatine phosphokinase, which helps your body produce energy. High levels may indicate muscle damage or injury.

Quick summary

["CPK helps assess muscle health and identify potential damage or conditions affecting your muscles."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
7475-7
Short code
Mackerel BasoBnd Ab Qn
Synonyms
Mackerel BasoBnd Ab Qn
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
22
Ref high
198
Critical range
— – 10000 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
lhr
CPT
82553
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What CPK Measures

Creatine phosphokinase (CPK) is an enzyme found primarily in heart, skeletal, and smooth muscle cells. It plays a role in energy production by transferring phosphate groups. When muscle tissue is damaged—due to injury, illness, or overexertion—the enzyme leaks into the bloodstream, raising CPK levels.

Why It’s Done

Your doctor may order a CPK test to investigate symptoms like muscle weakness, pain, or fatigue, or to monitor conditions such as heart attacks, muscle disorders, or certain infections.

Common Causes of Elevated CPK

High CPK levels can result from muscle injuries (e.g., strains, cramps), overexertion, or conditions like myositis (inflammation of muscles), rhabdomyolysis (severe muscle breakdown), or certain infections.

When to Follow Up

If your CPK levels are elevated, your doctor may recommend further testing or monitoring to determine the cause, such as additional muscle enzyme tests or imaging studies.

Reference range

Adult males: 22-198 U/L; Females: 22-198 U/LN/A

Specimen: whole-blood

No special preparation required. Inform provider of any chest pain or symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CPK (Creatine Phosphokinase)

Frequently asked questions

Why might my CPK test result be abnormal?
Abnormal CPK results may signal muscle damage or a related condition, but they can also be influenced by factors like recent exercise, certain medications, or underlying health issues. Always discuss your results with your healthcare provider.
What does a normal CPK level mean?
A normal CPK level typically indicates healthy muscle function without significant damage. However, reference ranges can vary by lab, so your doctor will interpret results in the context of your overall health.
Can diet or supplements affect CPK levels?
Dietary supplements or certain foods (e.g., high-protein diets) may temporarily affect muscle enzymes, but CPK levels are most directly influenced by muscle injury or illness. Avoiding strenuous activity before testing can help ensure accurate 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 17, 2026. · Read our editorial policy