Creatine phosphokinase test

How the Test is Performed

A blood sample is needed. This may be taken from a vein. The procedure is called a venipuncture.

This test may be repeated over 2 or 3 days for if you are a patient in the hospital.

How to Prepare for the Test

Usually, no special preparation is necessary.

Tell your doctor about any medications you are taking. Drugs that can increase CPK measurements include amphotericin B, certain anesthetics, statins, fibrates, dexamethasone, alcohol, and cocaine.

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

When the total CPK level is very high, it usually means there has been injury or stress to muscle tissue, the heart, or the brain.

Muscle tissue injury is most likely. When a muscle is damaged, CPK leaks into the bloodstream. Determining which specific form of CPK is high helps doctors determine which tissue has been damaged.

This test may be used to:

• Diagnose heart attack
• Evaluate cause of chest pain
• Determine if or how badly a muscle is damaged
• Detect dermatomyositis, polymyositis, and other muscle diseases
• Tell the difference between malignant hyperthermia and postoperative infection

The pattern and timing of a rise or fall in CPK levels can be diagnostically significant, particularly if a heart attack is suspected.

Except in unusual cases, other tests are used to diagnose a heart attack.

Normal Results

Total CPK normal values:

• 10 - 120 micrograms per liter (mcg/L)    

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

High CPK levels may be seen in patients who have:

• Brain injury or stroke
• Convulsions
• Delirium tremens
• Dermatomyositis or polymyositis
• Electric shock
• Heart attack
• Inflammation of the heart muscle (myocarditis)
• Lung tissue death (pulmonary infarction)
• Muscular dystrophies
• Myopathy

Additional conditions may give positive test results:

• Hypothyroidism
• Hyperthyroidism
• Pericarditis following a heart attack
• Rhabdomyolysis

Risks

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Considerations

Other tests should be done to determine the exact location of muscle damage.

Factors that may affect test results include cardiac catheterization, intramuscular injections, trauma to muscles, recent surgery, and heavy exercise.

Alternative Names

CPK test; Creatine kinase; CK test

References

Anderson JL. ST segment elevation acute myocardial infarction and complications of myocardial infarction. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 73.

Chinnery PF. Muscle diseases. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 429.

Update Date: 2/13/2013

Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.