Creatine phosphokinase (CPK), also known as creatine kinase or phosphocreatine kinase, is an enzyme found mainly in the heart, brain, and skeletal muscle. It catalyzes the conversion of creatine to phosphocreatine – an energy rich compound. Phosphocreatine powers the cells of the heart, brain, and skeletal muscle. If injury or stress occurs in these three organs, CPK leaks to the bloodstream. Measuring the amount of CPK in the blood is an important procedure to diagnose injury in the heart, brain, and skeletal muscle. Moreover, identifying the type of CPK found in the blood will indicate what specific organ has damage.
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Types of Creatine Phosphokinase and their Locations
CPK has three forms in the body called isoenzymes: CPK-1, CPK-2, and CPK-3. Isoenzymes are enzymes that are chemically different but function in the same way.
CPK-1 or CPK-BB is found mainly in the brain and lungs. Injury to these two organs results to elevation of CPK-1 level in the blood. CPK-1 is expected to increase in a person with brain cancer, brain injury (due to stroke or bleeding), seizure, pulmonary infarction, electroconvulsive therapy and others.
CPK-2 or CPK-MB is found in the heart. Increased CPK-2 in the blood can be due to heart attack, heart defibrillation (purposeful shocking of the heart by a healthcare provider) heart injury (due to accident), heart muscle inflammation or myocarditis (can be due to viral or bacterial infection), and heart surgery.
CPK- 3 or CPK-MM is found mainly in skeletal muscles. Blood CPK-3 level soars up due to crush injuries, strenuous exercise, surgery, seizures, intramuscular injuries, myositis, muscular dystrophy, muscle damage due to drug intake, and immobility for a long time (rhabdomyolisis).
Normal CPK Level
Normal blood CPK level varies by age, gender, and sex. Normal CPK values are usually between 38 to 174 IU/L for males and 96 to 140 for females. (Ref.) Take note that only your doctor can interpret the results. Women have slightly lower CPK values than men.
Hospitalized patients may have daily CPK test for a period of several days; this is done to monitor the improvement of the patient.
Medications That Can Affect CPK Test Results
The doctor advises the patient not to take certain medications before the test because they can interfere with the results. These medications include alcohol, cocaine, morphine, furosemide, dexamethasone, clofibrate, aspirin, anticoagulants, some anesthetics, ampicillin, and amphotericin. The patient should tell his doctor all the medications he takes before the test to avoid false positive results.[ad#afterpost]