Cpk

This test measures the level of the enzyme creatine phosphokinase, or CPK, in the blood. CPK is an enzyme found in the heart, brain, and skeletal muscle.

Who is a candidate for the test?

When muscle tissue is damaged, CPK can leak into the bloodstream. The test is usually done to see if muscle has been damaged or a heart attack has occurred.

How is the test performed?

To measure the amount of CPK in the blood, a blood sample is taken from a vein on the forearm or hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube, or tourniquet, is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow through them. A fine needle is gently inserted into a vein, and the tourniquet is removed. Blood flows from the vein through the needle and is collected in a syringe or vial for testing in the laboratory. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.

What is involved in preparation for the test?

Normally, no preparation is required for this test.

What do the test results mean?

Normal levels of CPK in the blood range from about 35 to 190 units per liter.

Abnormally high levels of CPK may indicate the following.

alcoholism

brain trauma

convulsions or seizures

delirium tremens, or severe withdrawal from alcohol

dermatomyositis, a disease in which the immune system attacks the muscles and the skin

electric shock

heart attack

muscular dystrophy

polymyositis, a disease in which the immune system attacks the muscles

lung damage

severe muscle breakdown from prolonged or strenuous exercise