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Serum Creatinine Phosphokinase (CPK) Activity

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

This test measures the activity of an enzyme called Creatine Phosphokinase (CPK), which helps assess muscle, heart, or brain cell damage.

Quick summary

["CPK levels can signal injuries to your muscles, heart, or nervous system."]

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

Key facts at a glance

LOINC
6355-2
Short code
C trach Ag Spec Ql IF
Synonyms
C trach Ag Spec Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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

Why This Test Might Be Ordered

Your doctor may request this test to diagnose or monitor conditions like heart attacks, muscle injuries (such as from overexertion or trauma), or neurological issues (like stroke). It can also help evaluate muscle diseases or track recovery after illness or surgery.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for a few hours before the blood draw if your doctor recommends it. Avoid strenuous exercise or consuming certain medications that could affect results for 24 hours prior.

What Happens During the Test

A healthcare professional will insert a needle into a vein in your arm to collect a small amount of blood. This usually takes less than five minutes. You may feel a brief pinch or discomfort, but it’s generally well-tolerated.

What the Results Mean

Higher than usual CPK levels may indicate damage to tissues where the enzyme is found (e.g., heart, muscle, or brain). Lower levels might suggest muscle wasting or certain metabolic conditions. Your doctor will interpret results in relation to your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CPK (Serum)

Frequently asked questions

What causes CPK levels to be higher than normal?
CPK levels can rise due to muscle damage from exercise, injuries, infections, or certain medications. Heart attacks (specifically the CPK-MB form) and neurological events like strokes can also elevate CPK levels. Always discuss symptoms with your doctor, as elevated levels may indicate an underlying issue requiring further evaluation.
What does it mean if my CPK levels are low?
Low CPK levels might suggest muscle atrophy, certain metabolic disorders, or conditions affecting muscle function. They can also occur in people with limited muscle mass or specific genetic disorders. Your doctor will consider your medical history and other test results to determine the cause.
How often should I get this test?
Your doctor will determine the frequency based on your health needs. This test may be part of routine check-ups, monitoring for chronic conditions, or follow-up after a suspected injury or illness. Follow your healthcare provider’s instructions for scheduling.
  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