Creatine kinase | Healthmatters.io (2024)

Creatine kinase (CK) is an enzyme found primarily in the brain, skeletal muscles, and heart. Conditions that cause damage to any of these three areas produce an elevated level of CK. For this reason, CK tests are often run to detect muscle damage, especially if someone is taking a drug such as a statin, using cocaine, or has been exposed to a toxin. If you’re experiencing chest pain or weakness your doctor may order a CK test to determine if you’ve had a heart attack. It is also common for doctors to use this test to evaluate the extent of sports injuries. Creatine kinase levels reflect the amount of muscle in the body, and as such men typically have higher levels than women. Finally, a CK test may be used to diagnose rhabdomyolysis, a condition characterized by the rapid breakdown of muscle tissue. It is worth noting that a normal level of CK does not necessarily mean that there is no muscle damage. It could mean that the damage occurred long enough ago for levels to return to normal. Frequently, a succession of CK tests are run as changes in CK levels due to muscle damage can take hours to present.

Normal Ranges:

Normal CK levels change drastically depending on factors such as age, gender, and activity level. Generally, 24-204 U/L is considered normal.

Creatine Kinase and liver enzymes (ALT and AST):

- A normal CK level with elevated ALT and AST enzymes would sway a doctor toward thinking there’s a liver problem;

- Ahigh CK with high ALT and AST levels suggests that something’s going on in the muscle.

Doing additional enzyme tests after a general screen can help a doctor decide whether the high ALT and AST are more likely the result of liver or muscle damage.

Of course, there could be a problem in both liver and muscle. Some metabolic muscle disorders, such as acid maltase deficiency and debrancher enzyme deficiency, affect both tissues. And two diseases can occur in the same person.

Most of the time, elevated ALT and AST levels in people with degenerating muscles do not mean much, other than that these enzymes, along with CK, are leaking out of the muscles. (The high levels of enzymes do no harm in and of themselves.) But sometimes, depending on results of other tests and the person’s history, they can mean there’s trouble in the liver or even in another organ.

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