Creatine Kinase
An enzyme concentrated in muscle. It rises after intense exercise or muscle injury, and is used to assess muscle and (in specific tests) heart damage.
Typical reference range
| Range | Unit |
|---|---|
| 50–400 (male) | U/l |
| 35–250 (female) | U/l |
What Creatine Kinase measures
Creatine kinase (CK) is an enzyme that helps supply energy to cells, and it is especially concentrated in muscle tissue, including both skeletal muscle and heart muscle. When muscle is stressed or damaged, CK leaks out of the cells and into the bloodstream, so a blood test can pick it up.
Because of this, CK is mainly used to help assess muscle injury, and in certain specific settings it can offer clues about heart muscle. Levels are naturally influenced by several factors, including how much muscle mass a person carries, ethnicity, and recent physical activity. That means a single value is best understood alongside your context and interpreted together with a clinician rather than on its own.
What a high Creatine Kinase can mean
A high CK most commonly reflects muscle exertion, such as intense or unaccustomed exercise, as well as physical injury or inflammation affecting muscle tissue. Because working muscle naturally releases some CK, a recent hard workout can raise the result without signalling a problem.
Other causes can include certain medications, for example statins in some people, along with underlying muscle disorders. In severe cases, a marked rise can point to rhabdomyolysis, a condition where muscle breaks down rapidly and releases its contents into the blood. Very high values need prompt medical attention. A clinician interprets your result in light of your symptoms, recent activity, medications, and overall picture, and may repeat the test or look at related markers before drawing any conclusions.
What a low Creatine Kinase can mean
A low CK is usually not a cause for concern. In many people it simply reflects lower muscle mass, since there is less muscle tissue available to release the enzyme into the bloodstream in the first place.
Occasionally a low result relates to certain underlying conditions, but this is far less common, and the clinical interest in CK is almost always focused on high values rather than low ones. Because of that, a result below the typical range rarely prompts action on its own. As with any single marker, it is best understood alongside your wider health picture and interpreted with a clinician, who can decide whether it fits your situation or whether anything further is worth reviewing.
Track your Creatine Kinase over time in Quanome — it reads your lab reports (PDF or photo) on your device, charts each marker against its range, and an AI coach explains what your trends mean alongside your Apple Health and DNA.