Creatine Kinase: What It Is and What a Test Is For

Your body produces the enzyme creatine kinase or creatine phosphokinase to keep your muscles functioning properly. Healthcare providers use the creatine kinase (CK) test to check levels of this enzyme in your blood. You may have elevated creatine kinase levels for various reasons.

This article discusses the types of CK enzymes, why a healthcare provider might order a CK test, what it checks for, how the test works, and how the results are interpreted.

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Creatine kinase is an enzyme that's responsible for healthy muscle function. When muscles break down, they release CK, elevating the protein levels in your blood.

Having a higher level of CK in your blood means you’ve experienced or are currently experiencing muscle damage.

There are three types of CK enzymes:

Healthcare providers order CK tests to check for muscle damage caused by diseases and injuries.

Elevated CK levels might signify:

CK levels won't always increase. For example, some diseases that affect the muscles may not cause elevated CK levels in the blood.

Your healthcare provider might test for elevated CK levels to check for muscle damage if they suspect you have a muscular disorder.

Symptoms of muscular disorders can include:

Reasons you might need a CK test:

Most healthcare providers now test for elevated cardiac troponin levels, another protein, instead of the CK-MB test when testing for signs of a heart attack.

Rhabdomyolysis (rhabdo) happens when damaged muscles break down and release their contents into your bloodstream.

Signs you're experiencing rhabdo may include:

You may also have no symptoms at all.

You're more likely to develop rhabdo if you:

During rhabdomyolysis, CK levels will typically be extremely high.

The CK test requires a simple blood sample. A healthcare professional will draw blood from a vein and send the sample to the laboratory for testing.

Your healthcare provider may need to perform the test multiple times since the CK levels don't immediately increase.

It's a good idea to avoid physical activity before getting a CK test. That's because exercise can cause muscle damage and may lead to an elevated level.

Risks of getting your blood drawn for a CK test are minimal but may include:

A CK test doesn't provide a diagnosis. But it does give the healthcare provider clues to form a diagnosis or order further testing.

Elevated levels of CK signify muscle damage. More specifically:

Laboratories may have different reference ranges for CK, so your results should be interpreted based on their reported reference range. One such CK range for adults is between 22 to 198 units per liter (U/L). What's normal for you can vary depending on your activity levels, sex, and race.

Your healthcare provider will likely order more tests to make a diagnosis since CK levels alone won't provide a complete picture of your condition.

The creatine kinase test is a blood test that checks whether the CK levels in your blood are elevated. Elevated CK levels can mean you have some sort of muscle damage in your body. It doesn't provide a full picture of your health, so healthcare providers typically perform other tests to make a diagnosis.

Before you go for any blood test, it's a good idea to tell your healthcare provider about any medications or supplements you’re taking. Some medications, supplements, and vitamins can impact CK levels in your blood, potentially affecting the result.

Not necessarily. Typical results can fall into a wide range and vary depending on your sex or race. Physical activity and certain medications can also raise levels. High levels are a starting point in the diagnostic process. Your healthcare provider will order more tests to determine why you have specific symptoms.

Several things can elevate your CK levels, including medication and strenuous exercise. Muscle damage can also cause levels to rise.

Treatment will depend on the underlying condition causing the elevated levels.

Again, this depends on the underlying condition causing your high levels. If you have high CK levels because of kidney failure, your healthcare provider may recommend a change in diet.

Muscular Dystrophy Association. Simply stated: the creatine kinase test.

University of Rochester Medical Center. Creatine kinase (blood).

MedlinePlus. Creatine kinase.

Beaumont. Neuromuscular disorders.

Centers for Disease Control and Prevention (CDC). Rhabdomyolosis.

By Steph CoelhoSteph Coelho is a freelance health and wellness writer and editor with nearly a decade of experience working on content related to health, wellness, mental health, chronic illness, fitness, sexual wellness, and health-related tech.She's written extensively about chronic conditions, telehealth, aging, CBD, and mental health. Her work has appeared in Insider, Healthline, WebMD, Greatist, Medical News Today, and more.