A creatine kinase (CK) test checks the level of the enzyme creatine kinase, which is found in heart tissue and skeletal muscles. This enzyme also can be found in smaller amounts in the brain. A blood test to check the level of CK can show if there has been damage to the heart, skeletal muscles, brain, and sometimes other parts of the body. The test is also called creatine phosphokinase (CPK).
CK is made up of three smaller types of enzymes, called isoenzymes: MM, MB, and BB. A doctor looks not only at the total level of CK but also at the level of these smaller parts to find a health problem.
CK might be used to help diagnose a heart attack. This topic focuses on CK tests for other reasons than heart attack.
Why It Is Done
Many things can cause an increase in total creatine kinase (CK) and in the isoenzymes. This test is often used to look for damage to muscles. For example, it might be used to see if someone who has muscle pain has serious muscle damage.
The isoenzyme MM is raised in most conditions that also cause an increase in total CK.
MB can be raised in problems such as injury to muscles (including after surgery), muscular dystrophy, chronic kidney failure, or an infection in the heart.
BB may be raised in problems such as brain injury, bleeding in the brain, and some types of cancer.
How To Prepare
In general, there's nothing you have to do before this test, unless your doctor tells you to.
How It Is Done
A health professional uses a needle to take a blood sample, usually from the arm.
How It Feels
When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.
There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.
Each lab has a different range for what's normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn't in the normal range may still be normal for you.
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