Creatine kinase (CK) is an enzyme that’s found in your skeletal muscle, heart muscle and brain. When any of these tissues are damaged, they leak creatine kinase into your bloodstream. Elevated CK levels may indicate muscle injury or disease.
Creatine kinase (CK) is an enzyme that mainly exists in your heart and skeletal muscle, with small amounts in your brain. The cells in your skeletal muscles, heart muscles or brain release creatine kinase into your blood when they’re damaged.
An enzyme is a protein that acts as a catalyst to bring about a specific biochemical reaction.
The small amount of CK that’s normally in your blood mainly comes from your skeletal muscles (the muscles that are attached to your bones and tendons). Any condition, injury or event that causes muscle damage and/or interferes with muscle energy production or use increases levels of CK in your blood. For example, intense exercise can increase CK levels. Muscle diseases (myopathies) such as muscular dystrophy can also increase CK levels.
There are three types of CK enzymes:
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A creatine kinase (CK) test measures the amount of creatine kinase in your blood.
Elevated CK levels may indicate skeletal muscle, heart or brain damage or degeneration — either chronic (long-term) or acute (short-term).
Other names for a creatine kinase test include:
The regular function of creatine kinase (CK) is not really related to what elevated levels of it may indicate in a blood test. CK’s job is to add a phosphate group, a group of natural chemicals, to creatine, a substance in your muscle cells that helps your muscles produce energy. When CK adds phosphates to creatine, it turns the creatine into the high-energy molecule, phosphocreatine, which your body uses to generate energy.
CK gets into your bloodstream when your muscles, heart or brain experience acute damage or chronic degeneration. When your muscles are damaged, the muscle cells break open, and their contents, including creatine kinase, leak into your bloodstream.
Healthcare providers most often use creatine kinase (CK) tests to diagnose and monitor the following muscle issues:
Since muscle-related symptoms can be symptoms of several different conditions, your provider may order other tests along with a CK test, including:
Muscular diseases (myopathies) include:
Muscular injuries can result from the following situations:
Types of muscular inflammation (myositis) include:
Healthcare providers sometimes use a creatine kinase (CK) test to help diagnose a heart attack, though not very often. CK testing used to be a common test for heart attacks, but healthcare providers now use another test, called troponin, which is better at detecting heart damage.
Your healthcare provider may order a creatine kinase (CK) test for you if you have symptoms of a muscular disorder, which include:
Your provider may also order this test if you’ve had a muscle injury or stroke. CK levels may not peak until up to two days after certain injuries, so you may need to do the test more than once.
A healthcare provider called a phlebotomist usually performs blood draws, which include those for a creatine kinase (CK) blood test, but any healthcare provider who is trained in drawing blood can perform this task. They then send the samples to a lab where a medical laboratory scientist prepares the samples and performs the tests on machines known as analyzers.
In most cases, you don’t need to do anything special to prepare for a creatine kinase (CK) blood test.
If your healthcare provider has ordered a CK test to diagnose a potential muscle disorder, you should limit your exercise to normal activities before the test, since muscle strain from exercise can temporarily increase CK levels in your blood.
You can expect to experience the following during a blood test, or blood draw:
The entire procedure usually takes less than five minutes.
After a healthcare provider has collected your blood sample, they’ll send it to a laboratory for testing. Once the test results are back, your healthcare provider will share the results with you.
Blood tests are a very common and essential part of medical testing and screening. There’s very little risk to having blood tests. You may have slight tenderness or a bruise at the site of the blood draw, but this usually resolves quickly.
In most cases, you should have your creatine kinase test results within one or two days, though it could take longer.
Blood test reports, including creatine kinase test reports, usually provide the following information:
In a healthy adult, normal creatine kinase (CK) levels can vary due to a few factors, including your:
Ranges also vary from lab to lab due to different test methods. Always check the given reference range on your lab report test results. The normal creatine kinase (CK) ranges are generally higher in people assigned male at birth than in people assigned female at birth.
People who have greater muscle mass normally have higher CK levels than those who don’t.
Having a high level of creatine kinase (CK), or a rise in levels in subsequent CK tests, generally indicates that you have experienced some recent muscle damage. A CK test can’t indicate which muscle(s) was damaged or the cause of the damage.
Healthcare providers often have you get multiple CK tests to check the progress of your levels. If you have multiple test results that peak and then begin to drop, it usually means your muscle damage has diminished. If your CK levels increase or stay at a persistently high level, it may indicate that you have ongoing muscle damage or muscle degeneration.
If your results show you have higher-than-normal levels of CK, your provider may order tests to check the levels of specific CK enzymes in order to determine the type of muscles affected, including:
Certain conditions and injuries that aren’t directly related to your muscles can cause elevated CK levels, including:
If your creatine kinase (CK) test results reveal that you have high levels of CK, it doesn't necessarily mean that you have a medical condition. Many other factors, such as exercise, certain medications and shot injections, can temporarily increase your CK levels. There could’ve also been an error in the processing of the test.
When interpreting your results, your healthcare provider will consider several factors, including your current medications, lifestyle and symptoms. They will let you know if you need further testing.
If you have questions about your results, don’t be afraid to talk to your healthcare provider.
Experiencing muscle pain and weakness is usually temporary. If you’re experiencing prolonged muscle issues, talk to your healthcare provider about your symptoms. They may order a creatine kinase test and other tests to try to determine the cause of your symptoms.
A note from Cleveland Clinic
Seeing an abnormal test result can be stressful. Know that having a high level of creatine kinase doesn’t necessarily mean you have a medical condition and need treatment. Your healthcare provider will let you know if you need to undergo further tests to determine the cause of the abnormal level. Don’t be afraid to ask your provider questions. They’re available to help you.
Last reviewed by a Cleveland Clinic medical professional on 04/11/2022.
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