Creatine Kinase Test

Other names: CK Test

Creatine kinase is an enzyme, which is found in the heart, skeletal muscles and the brain. There are three main forms of creatine kinase enzyme; these are known as isoenzymes. The isoenzymes are known as CK-MB, which is mostly found in the heart muscle, CK-BB, which is found mostly in the brain and CK-MM, which is found both in the heart and the skeletal muscles. Most of the CK in the blood comes from the muscles; it is very rare for CK in the brain to get into the bloodstream.

When is the test used?

The creatine kinase test is primarily used to see whether a patient has had a heart attack but it may also be used to see if the muscles have sustained damage.

The test is usually ordered if a patient has chest pain and the doctor suspects they have had a heart attack.

How is the test done?

The test is performed by collecting a sample of blood from the arm; a needle is inserted into a vein in the arm (usually on the inside of the elbow) and the blood is drawn out and collected in a syringe. Once the sample has been collected, it will be bottled and labelled with the patient’s name before being sent away to the laboratory for analysis.

What do the test results show?

After a heart attack, levels of CK in the bloodstream start to increase; it usually takes around 4-6 hours for the levels to begin to rise and they reach peak concentration after 18 hours. It usually takes around 2 days for the levels of CK in the blood to return to normal after a heart attack. Levels of CK also rise if the muscles have been damaged.

If the test indicates high levels of CK, this usually means that the heart muscle or other muscles in the body have been damaged or used excessively (CK levels are higher after prolonged, strenuous exercise for example). If the doctor suspects that the patient has had a heart attack, they will usually order additional tests to confirm the diagnosis.

People who have greater muscle mass (athletes, for example) generally have slightly higher levels of CK in their blood and Afro-Caribbean people generally have higher levels of CK than other ethnic groups.

CK levels may also be affected by certain medications and drinking alcohol.

Specific Blood Tests

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