CK-MB Test
At a Glance
Why Get Tested?
To find out if you have had a heart attack
When to Get Tested?
If you have chest pain and your CK levels are high
Sample Required?
A blood sample taken from a vein in the arm
The Test Sample
What is being tested?
CK–MB is one of three separate forms of the enzyme creatine kinase (CK). CK–MB is found mostly in heart muscle. It rises when there is any damage to heart muscle cells.
How is the sample collected for testing?
A blood sample is taken by needle from 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.
The Test
How is it used?
CK–MB levels, along with total CK, are tested in persons who have chest pain to diagnose whether they have had a heart attack. A high total CK could indicate damage to either the heart or other muscles, but because CK-MB comes from the heart, a high CK–MB suggests that the damage was to heart muscle.
When is it requested?
CK-MB may be requested with total CK, in persons with chest pain to find out whether the pain is due to a heart attack. It may also be used in a person with a high CK to discover whether damage is to the heart or other muscles.
Although CK-MB is a very good test, it has largely been replaced by troponin, which is an ever better test for damage to the heart.
What does the test result mean?
If CK-MB is raised, and the ratio of CK-MB to total CK is high, the heart is the muscle which is likely to be damaged. A high CK with a low CK-MB suggests that other muscles were damaged.
Is there anything else I should know?
If your doctor suspects injury to both heart muscle and other muscles in the body, troponin is a more accurate test for a heart attack.
Persons whose kidneys have failed can have high CK-MB levels without having had a heart attack. Rarely, long-term muscle disease, low thyroid hormone (T4) levels, and alcohol abuse can increase CK-MB, producing changes similar to those seen in a heart attack.
Common Questions
Ask a Laboratory Scientist
Article Sources
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
