The CPK isoenzymes test measures the different forms of creatine phosphokinase (CPK) in the blood. CPK is an enzyme found mainly in the heart, brain, and skeletal muscle.
Creatine phosphokinase – isoenzymes; Creatine kinase – isoenzymes; CK – isoenzymes
How the test is performed
A blood sample is needed. This may be taken from a vein. The test is called a
If you are in the hospital, this test may be repeated over 2 or 3 days. A significant rise or fall in the total CPK or CPK isoenzymes can help your health care provider diagnosis certain conditions.
How to prepare for the test
Usually, no special preparation is necessary.
Tell your doctor about all the medications you are taking. Certain medications can interfere with test results. Drugs that can increase CPK measurements include the following:
- Amphotericin B
- Certain anesthetics
- Fibrate drugs
- Steroids such as dexamethasone
This list is not all-inclusive.
How the test will feel
When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
This test is done if a
CPK is made of three slightly different substances:
- CPK-1 (also called CPK-BB) is found mostly in the brain and lungs
- CPK-2 (also called CPK-MB) is found mostly in the heart
- CPK-3 (also called CPK-MM) is found mostly in skeletal muscle
What abnormal results mean
Higher-than-normal CPK-1 levels:
Because CPK-1 is found mostly in the brain and lungs, injury to either of these areas can increase CPK-1 levels. Increased CPK-1 levels may be due to:
Brain cancer Brain injury(due to injury, stroke, or bleeding in the brain)
- Electroconvulsive therapy
- Pulmonary infarction
Higher-than-normal CPK-2 levels:
CPK-2 levels rise 3 – 6 hours after a
Increased CPK-2 levels may also be due to:
defibrillation(purposeful shocking of the heart by medical personnel)
Heart injury (for instance, from a car accident)
Inflammation of the heart muscle usually due to a virus (myocarditis)
Open heart surgery
CPK-2 levels do NOT usually rise with
Higher-than-normal CPK-3 levels are usually a sign of muscle injury or muscle stress and may be due to:
- Muscle damage due to drugs or being immobile for a long time (
rhabdomyolysis) Muscular dystrophy Myositis(skeletal muscle inflammation)
- Receiving many intramuscular injections
- Recent nerve and muscle function testing (electromyography)
- Recent seizures
- Recent surgery
- Strenuous exercise
Factors that can affect test results include
Isoenzyme testing for specific conditions is about 90% accurate.