This test measures the level of the enzyme creatine phosphokinase, or CPK, in the blood. CPK is an enzyme found in the heart muscle, brain tissue, lung tissue, and skeletal muscle.
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.
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 After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.
Normally, no preparation is required for this test.
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. alcoholismbrain traumaconvulsions or seizuresdelirium tremens, or severe withdrawal from alcoholdermatomyositis, a disease in which the immune system attacks the muscles and the skinelectric shockheart attackmuscular dystrophypolymyositis, a disease in which the immune system attacks the muscleslung damagesevere muscle breakdown from prolonged or strenuous exercisesever muscle breakdown from a condition called rhabdomylosismyocarditis, an inflammatory condition of the heart musclepericarditis, an inflammatory condition of the sac that surrounds the heartmuscle inflammation from certain drugs, particularly statin therapy