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Creatine Kinase (Blood)

Does this test have other names?

Creatine phosphokinase, CK, CPK

What is this test?

This test measures the amount of an enzyme called creatine kinase (CK) in your blood.

CK is a type of protein. The muscle cells in your body need CK to function. Levels of CK can rise after a heart attack, skeletal muscle injury, strenuous exercise, or drinking too much alcohol, and from taking certain medicines or supplements. If this test shows that your CK levels are high, you may have muscle or heart damage. CK is made up of three enzyme forms. These are CK-MB, CK-MM, and CK-BB. CK-MB is the substance that rises if your heart muscle is damaged. CK-MM rises with other muscle damage. CK-BB is found mostly in the brain.

Why do I need this test?

You may need this test if you have chest pain or weakness and your doctor needs to find out if you've had a heart attack.

Your doctor may also order this test if you have had a stroke or sports injury. But because levels of this protein may not peak for up to 2 days after certain injuries, you may need this test several times to see if your heart or other muscles have been damaged.

If you are taking statin medicines and have unusual muscle cramping and pain or muscle weakness, your doctor may also order a CK test. Statin medicines are used to treat high cholesterol. They sometimes cause serious muscle injury. In very rare cases they can even lead to a rapid, life-threatening muscle breakdown.

What other tests might I have along with this test?

Your doctor may order other tests to find out if you have had a heart attack or muscle injury. If you have had a heart attack, your doctor may order a blood test to look for high levels of cardiac troponin. This is another protein is found in your heart. Cardiac troponin has replaced CK-MB as the test of choice to find out if you’ve had a heart attack. This is because cardiac troponin is more sensitive and more specific.

Or the doctor may order tests to see how you are recovering. These tests include:

  • Other blood tests

  • Electrocardiogram (ECG), to measure the electrical activity of your heart

Because levels of CK may rise if you have a thyroid problem, alcohol abuse, or kidney failure, your doctor may also order tests to look for these diseases.

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your healthcare provider.

The normal range for general CK varies by age and gender.  Race is also known to affect CK levels. 

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.

What might affect my test results?

Strenuous exercise, recent surgery, and certain drugs may make your CK levels higher than normal.

African Americans naturally have higher levels of CK. Some people with a muscular build also have higher levels of CK.

How do I get ready for this test?

You don't need to prepare for this test. But be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use. 

Medical Reviewers:

  • Hanrahan, John, MD
  • Taylor, Wanda L, RN, PhD