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Alternative namesCreatine phosphokinase - isoenzymes; Creatine kinase - isoenzymes; CK - isoenzymes
DefinitionThis blood test measures the isoenzymes (different forms) of creatine phosphokinase .
How the test is performed
Blood is drawn from a vein, usually in the arm. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band or blood pressure cuff) is placed around the upper arm to apply pressure and cause veins below the tourniquet to fill with blood.
A needle is inserted into the vein, and the blood is collected in an airtight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation and facilitate the collection of blood. Once the proper amount of blood has been drawn, the needle is removed, and the puncture site is covered to stop any bleeding.
Infant or young child:
This test may be repeated over 2 or 3 days for hospitalized patients. A significant rise or fall in the total CPK or CPK isoenzymes can be very helpful to health care providers for the diagnosis of certain conditions.
How to prepare for the test
Usually, no special preparation is necessary.
Infants and children:
How the test will feelWhen the needle is inserted to draw blood, some people may feel moderate pain, while others may feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
CPK isoenzymes are performed when the total CPK level is elevated. Isoenzyme testing can help differentiate the source of the damaged tissue.
CPK is an enzyme found predominantly in the heart, brain, and skeletal muscle. CPK is composed of 3 isoenzymes that differ slightly in structure:
Because the CPK-1 isoenzyme is predominately found in the brain and lungs, injury to either of these organs (for example, stroke or lung injury due to a pulmonary embolism) are associated with elevated levels of this isoenzyme.
CPK-2 levels rise 3 to 6 hours after a heart attack . If there is no further damage to the heart muscle, the level peaks at 12 to 24 hours and returns to normal 12 to 48 hours after tissue death. CPK-2 levels do not usually rise with chest pain caused by angina , pulmonary embolism (blood clot in the lung), or congestive heart failure .
The CPK-3 isoenzyme is normally responsible for almost all CPK enzyme activity in healthy people. When this particular isoenzyme is elevated, it usually indicates injury or stress to skeletal muscle.
What abnormal results meanHigher-than-normal CPK-1 levels may occur with the following:
Higher-than-normal CPK-3 levels may occur with the following:
Factors that can affect test results include cardiac catheterization , intramuscular injections, recent surgery, and vigorous and prolonged exercise or immobilization.
Drugs that can increase CPK measurements include the following:
Isoenzyme testing for specific conditions is about 90% accurate.
Update Date: 5/20/2003Bridget Martell, M.D., Department of Internal Medicine, Albert Einstein College of Medicine, New York, NY. Review provided by VeriMed Healthcare Network.
Last updated: Tue, 06 Jan 2009 00:20:03 GMT