Ck Isoenzymes Cpk Isoenzymes

Overview & Description

This test measures the blood levels of three forms of the enzymecreatine phosphokinase, which is also called CPK. These forms are known asisoenzymes. They are called CPK-BB, CPK-MB, and CPK-MM.

This blood test determines the amounts of each of theseisoenzymes in the blood. These levels can help a doctor to diagnose certainillnesses and conditions.

  • CPK-BB is found mainly in the brain and lungs.
  • CPK-MB is found mainly in the heart.
  • CPK-MM is found mainly in skeletal muscle.
  • Damage to the brain, lungs, heart, or muscle may cause thecorresponding isoenzyme to leak into the bloodstream.

    How is the test performed?

    In order to measure the amount of CPK isoenzymes in the blood,a blood sample is taken from a vein on the forearm or hand. First, the skin overthe vein is cleaned with an antiseptic. Next, a rubber tube called a tourniquet istied around the upper arm. This enlarges the veins in the lower arm by restrictingblood flow through them. A fine needle is gently inserted into a vein, and thetourniquet is removed. Blood flows from the vein through the needle and iscollected in a syringe or vial for testing in the laboratory. After the needle iswithdrawn, the puncture site is covered for a short time to prevent bleeding.

    Preparation & Expectations

    What is involved in preparation for the test?

    Normally, no preparation is required for this test.

    Results and Values

    What do the test results mean?

    If a disease process is taking place, the total amount of CPK willbe high, and the individual isoenzyme increases are used to determine what partof the body is responsible for the increase in total CPK. For example, when aheart attack occurs, the total CPK becomes high because of an increase in theCPK-MB and CPK-MM isoenzymes. The normal total CPK level is roughly 25 to175 units per liter. Normal values for each of the isoenzymes are as follows:

  • CPK-BB: 0% of the total CPK
  • CPK-MB: 0% to 6% of the total CPK
  • CPK-MM: 96% to 100% of the total CPK
  • Abnormally high levels of CPK-BB may sometimes be seen in the following:

  • lung damage from a blood clot
  • shock
  • after cardiopulmonary resuscitation
  • Abnormally high levels of CPK-MB may indicate the following:

  • heart attack
  • any other trauma to the heart, such as from heart surgery
  • electrical injuries
  • Abnormally high levels of CPK-MM may indicate the following:

  • heart attack
  • muscle damage
  • intramuscular injections
  • muscular dystrophy
  • myositis,an inflammation in the muscles usually due to infection or immune systemdisease
  • convulsions
  • recent surgery
  • rhabdomyolysis,which is widespread muscle destruction, usually due to alcoholism or exercise
  • strenuous exercise
  • Article type: xmedgeneral