Muscle
Creatine kinase blood test
A creatine kinase (CK) blood test measures an enzyme released when muscle is stressed or damaged. It rises after hard exercise, injury and certain medicines, and a markedly high level can signal significant muscle breakdown, which makes it useful for athletes, recovery monitoring and investigating muscle symptoms.
- What it measures
- Creatine kinase, an enzyme released by muscle
- Sample
- Venous blood sample
- Fasting
- Not required (avoid strenuous exercise for 24–48 hours before)
- Also known as
- CK, creatine phosphokinase, CPK
- Included in 57 Health tests
- 3 panels, from £95
Creatine kinase reference range
Guide only| Category | Guide range |
|---|---|
| Adults (guide) | 40–320 U/L |
CK is naturally higher in men, in people with more muscle mass, and in some ethnic groups, and it rises sharply after exercise, injury or intramuscular injections. For a meaningful baseline, avoid strenuous exercise for 24–48 hours beforehand. Ranges vary by laboratory.
These are general UK adult guide ranges from public health sources, shown for orientation only. Reference ranges vary by laboratory, assay, age and sex, so your result is always interpreted against the range quoted by the analysing laboratory on your report.
What does a high creatine kinase level mean?
A high CK usually reflects recent muscle activity or minor muscle stress: intense exercise is the most common cause, and levels return to normal with rest.
Larger rises can follow injury, intramuscular injections, or muscle-affecting medicines such as some statins; a very high CK can indicate significant muscle breakdown (rhabdomyolysis) and needs prompt attention. Context and repeat testing after rest help interpret it.
What does a low creatine kinase level mean?
A low CK is not a concern and needs no action.
It can simply reflect lower muscle mass or a period of inactivity.
When to consider a creatine kinase test
- Monitoring training load and recovery
- Muscle pain, weakness or unusually dark urine
- Checking muscle effects of statins or other medicines
- After heavy exertion or a suspected muscle injury
Frequently asked questions
This page is general information about a blood marker and is not medical advice or a diagnosis. A creatine kinase test screens and gives context; results are interpreted by a clinician alongside your symptoms, history and other markers. Always follow the guidance on your own report.