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Muscle Creatine Kinase (CK) – Serum/plasma

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

This test measures the amount of creatine kinase, an enzyme produced by heart, skeletal muscle, and brain, which helps assess muscle damage or other conditions affecting these tissues.

Quick summary

["CK levels can signal muscle injury or other health concerns."]

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

Key facts at a glance

LOINC
42139-6
Short code
Deprecated US Muscle PC Bx
Synonyms
Deprecated US Muscle PC Bx
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us
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 Matters

CK is released into the bloodstream when muscle cells are damaged. Elevated levels may indicate conditions like muscle strains, heart attacks, or other injuries to these tissues. Your doctor may order this test to diagnose or monitor these conditions.

Common Causes of Abnormal Results

High CK levels can result from muscle injuries (e.g., strains, tears), overexertion, certain medications, or underlying conditions like myopathies or heart problems. Low levels are less common but may occur with muscle wasting or certain metabolic disorders.

When You Might Need This Test

Your doctor may recommend this test if you experience symptoms like muscle pain, weakness, or cramps, especially after physical activity. It’s also used in diagnosing conditions like heart attacks, muscle diseases, or neurological disorders.

What to Expect Before the Test

No special preparation is needed, but avoid intense exercise or strenuous activity 24 hours before the test. If you’re on medications that affect muscle function, let your doctor know.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CK Level

Frequently asked questions

How long does it take to get results?
Results are typically available within 1–2 business days, depending on your lab’s processing time. Follow-up with your doctor to discuss findings.
Can I take my usual medications before this test?
Yes, but inform your doctor about all medications, including over-the-counter drugs or supplements, as some may affect CK levels.
Does this test involve fasting?
No fasting is required for this test. However, avoid consuming large amounts of alcohol or caffeine before testing, as they may influence muscle enzyme levels.
  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