Insight into your CK level.
CK is an enzyme released when muscle tissue is damaged. It rises after heavy exertion and can be raised with persistent muscle complaints.
Also known as: creatine kinase, CPK, creatine phosphokinase, CK level
Personal assessment by our BIG-registered Bloodworks® doctors
By the Bloodworks editorial team
Creatine kinase (CK) blood test
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- 69,-
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- No referral needed
- 1000+ collection points
- Results typically within 2 working days
- Every result reviewed by a BIG-registered doctor
Broader sports test
View Bloodworks Sport
CK says something about muscle damage at one moment. To see recovery, iron status and hormones together, a broader sports test gives more direction.
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Background
What is creatine kinase?
Creatine kinase, or CK, is an enzyme found mainly in muscle tissue: in skeletal muscle, in heart muscle and in smaller amounts in the brain. It plays a role in supplying energy to the muscle cell. When a muscle cell is damaged, CK leaks into the blood and the level rises. How far it rises says something about the extent of the damage, not about its location or cause.
That makes CK a sensitive but broad marker. A markedly raised value nearly always traces back to muscle, but does not in itself say whether that is due to hard training, a fall, a medicine or an underlying muscle condition. The result gains meaning from what you did in the preceding days and what symptoms you have.
In brief
Muscle enzyme
Mainly in skeletal muscle, also in heart muscle
Leaks on damage
Released when muscle cells are damaged
Exertion weighs heavily
Rises sharply after unusual or heavy training
Broad, not specific
Shows damage, not the location or the cause
Common reasons to test
When can insight into your CK be valuable?
Below are some situations in which measuring CK can provide insight.
With persistent muscle complaints
Muscle pain or weakness that does not settle can be a reason to check whether muscle damage is measurable.
On cholesterol lowering medication
Statins cause muscle complaints in a small group. CK shows whether muscle damage accompanies them. Always discuss your medication with your doctor.
After heavy training
Unusual or very intense exertion can keep the CK value raised for days. Athletes use the value to track recovery.
For endurance athletes
Those who train often and hard can measure CK periodically to follow how the body responds to training load and whether there is enough recovery between sessions.
After a fall or accident
Together with a doctor, CK can help to assess muscle damage after a fall or accident.
With fatigue and muscle weakness
As part of broader testing for fatigue accompanied by muscle weakness, a CK measurement can show whether the muscles may play a role.
What your result means
CK too high: what your value means
CK is expressed in units per litre (U/L). The laboratory states the reference values that apply there; these differ between men and women and are naturally higher in people with a lot of muscle mass. For a usable result it helps to avoid unusually heavy exertion in the 48 hours before the draw.
A low value
A low CK rarely gives cause for concern and fits with limited muscle load. Our doctor provides explanation and context with your result.
A normal value
A CK within the laboratory reference values fits with no measurable muscle damage at the time of the draw.
A raised value
A raised CK most often fits with exertion in the days before the draw. Our doctor indicates in your report what fits your result.
How we interpret your result
Our doctors assess your CK against the laboratory reference values and your personal context: what you did in the days before the draw, your muscle mass, your symptoms and any medication. Without that context a single CK value is hard to interpret.
Related tests
Often combined with CK.
A single marker gives one perspective. For a broader picture you can combine CK with a theme package or related markers.
+ 29,- blood draw fee per orderFree from 225,-
Frequently asked questions
Everything you want to know
Do I need to fast for a CK test?
Fasting is not needed. More important is to avoid unusually heavy or unfamiliar exertion in the 48 hours before the draw: that can raise the value considerably and makes the result harder to interpret.
Does a raised CK mean something is wrong with my muscles?
Not necessarily. The most common explanation is exertion in the preceding days. CK shows that muscle tissue has been damaged, not what caused it. If the value stays raised without a clear explanation, our doctor assesses that in the context of your situation.
Does CK say anything about my heart?
Not reliably. CK is also present in heart muscle, but other, more specific tests are used to assess the heart.
I take a statin and have muscle pain. Can I stop by myself?
No. Always discuss this first with the doctor who prescribed it. A CK measurement can provide information, but the decision about your medication belongs with your own doctor.
What exactly does a CK test measure?
CK stands for creatine kinase, an enzyme found mainly in muscle tissue, where it helps supply energy to the muscle cell. When muscle tissue is damaged or heavily loaded, CK leaks into the blood. The test measures how much of this enzyme is circulating in your blood and so gives an impression of muscle load or muscle damage at that moment.
Why is CK raised after sport and how long does that last?
Heavy or unfamiliar exertion causes small amounts of damage in the muscle fibres. That is part of training, but it lets CK leak into the blood. The value climbs in the hours to days after the exertion and can then stay raised for several days, sometimes longer after very heavy exertion. The more unfamiliar the exertion is for your body, the stronger the rise usually is.
Should I rest before the test?
Yes, that is sensible. Avoid heavy or unfamiliar exertion in the 48 to 72 hours before the draw, such as an intense strength session or a long endurance run. This prevents a normal training response from distorting the result and gives a value that better reflects your usual situation.
What does a low CK value mean?
Usually little. A low CK fits with limited muscle load in the days before the draw or with a smaller muscle mass, and is rarely a reason for follow-up. Our doctor comments on it in your report if your result gives cause to.
Where do you give blood?
You can give blood at collection points across the Netherlands, usually without an appointment.
Find a collection point near you or read how a blood draw works.
Want to test multiple markers at once?
Combine CK with other markers via Bloodworks Select. The blood draw and collection fee is charged once per order, and is waived from 225,-.
Ready for insight into your CK level?
You receive your CK level with a personal explanation from a doctor, usually within 2 working days. No referral needed.