Creatine Kinase

Test Overview

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. For more information on the CK test for heart attack, see Cardiac Enzyme Studies.

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

You do not need to do anything special to prepare for this test.

How It Is Done

The health professional taking a sample of your blood will:

Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
Clean the needle site with alcohol.
Put the needle into the vein. More than one needle stick may be needed.
Attach a tube to the needle to fill it with blood.
Remove the band from your arm when enough blood is collected.
Put a gauze pad or cotton ball over the needle site as the needle is removed.
Put pressure on the site and then put on a bandage.

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Risks

There is very little chance of a problem from having a blood sample taken from a vein.

You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. You can use a warm compress several times a day to treat this.

Results

A creatine kinase (CK) test checks the level of the enzyme creatine kinase, which is found in heart tissue and skeletal muscles.

Normal

The range for "normal" varies from lab to lab. Your lab may have a different range. Your lab report should show what range your lab uses for "normal." Also, your doctor will evaluate your results based on your health and other factors.

What Affects the Test

You may not be able to have the test, or the results may not be helpful, if:

You abuse alcohol or other substances.
You do hard exercise.
You had surgery recently.
You have shots (injections) into your muscles.
You have a lot of muscle mass.

What To Think About

Different types of health problems can raise creatine kinase (CK) levels. Your doctor will look at your CK test results along with the results of other tests, your symptoms, and your health history.