Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.
Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
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:
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 test reveals that your total CPK level is elevated. CPK isoenzyme testing can help pinpoint the exact source of the damaged tissue.
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:
Cannon CP, Lee TH. Approach to the patient with chest pain. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 49.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.