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The Test Sample
What is being tested?
Creatine kinase-MB (CK-MB) is a form of an enzyme found primarily in heart muscle cells. This test measures CK-MB in the blood.
CK-MB is one of three forms (isoenzymes) of the enzyme creatine kinase (CK). These isoenzymes include:
- CK-MM (found in skeletal muscles and the heart)
- CK-MB (found mostly in the heart, but small amounts found in skeletal muscles)
- CK-BB (found mostly in the brain and smooth muscle, such as the intestines and uterus)
CK is released from muscle cells and is detectable in the blood whenever there is muscle damage. The small amount of CK that is normally in the blood is primarily CK-MM. CK-BB almost never gets into the blood, and CK-MB will typically only be present in significant amounts when the heart is damaged. A CK test measures the total level but does not distinguish between the three isoenzymes. When there is an increased amount of CK present in the blood, the CK-MB test can be used to determine whether it is due to heart damage or is more likely to be related to skeletal muscle injury.
How is the sample collected for testing?
A blood sample is taken by needle from a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is usually needed because the test is done in emergency care.