Blood test
Creatine Kinase Test
A creatine kinase (CK) test measures an enzyme released when muscle is damaged, used to investigate muscle problems.
Quick answer
Creatine Kinase Test: what it is and what the results mean
Creatine kinase (CK) is an enzyme found mainly in muscle. When muscle cells are damaged, CK leaks into the blood, so a raised level indicates muscle injury or disease.
- Why it is done: It is used to investigate muscle pain, weakness or dark urine, to help diagnose muscle diseases (myopathies), to monitor for muscle side effects of certain medicines such as statins, and to assess muscle breakdown (rhabdomyolysis).
- Understanding results: A raised CK indicates muscle damage, with very high levels suggesting significant breakdown.
What it is
Creatine kinase (CK) is an enzyme found mainly in muscle. When muscle cells are damaged, CK leaks into the blood, so a raised level indicates muscle injury or disease.
Why it is done
It is used to investigate muscle pain, weakness or dark urine, to help diagnose muscle diseases (myopathies), to monitor for muscle side effects of certain medicines such as statins, and to assess muscle breakdown (rhabdomyolysis).
What to expect
It is an ordinary blood test from a vein in the arm. Strenuous exercise beforehand can raise CK, so you may be advised to avoid heavy activity before the test.
Understanding the results
A raised CK indicates muscle damage, with very high levels suggesting significant breakdown. The cause is worked out alongside symptoms, medicines and other tests. A normal level makes significant ongoing muscle damage unlikely.
Good to know
Risks and limitations
It is a safe blood test, but CK is not specific to one condition — it rises after exercise, injury, injections and many muscle disorders, so it is interpreted in context.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
Creatine Kinase Test: frequently asked questions
Can exercise raise my CK level?
Yes. Strenuous or unaccustomed exercise can temporarily raise CK, so you may be asked to avoid heavy activity before the test to avoid a misleadingly high result.
Why is CK checked when taking statins?
Statins can occasionally cause muscle inflammation. If you develop muscle pain or weakness, CK is measured to check for muscle damage and guide whether the medicine should be adjusted.
Related tests
Other blood test investigations
Sources
Where this is drawn from
- NHS — Tests and treatments
- NICE — diagnostic guidance
- Association for Laboratory Medicine / relevant professional body
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