At a Glance
Why Get Tested?
To distinguish between skeletal muscle and heart muscle damage; sometimes to determine if you have had a heart attack (if the troponin test is not available); sometimes to monitor for additional heart damage
When to Get Tested?
When you have an increased creatine kinase (CK) level and your doctor wants to determine whether it is due to skeletal or heart muscle damage; sometimes at intervals to monitor heart damage
A blood sample drawn from a vein in your arm
Test Preparation Needed?
The Test Sample
What is being tested?
Creatine kinase-MB (CK-MB) is found primarily in heart muscle cells. It 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 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 needed.
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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.
Sources Used in Current Review
Dugdale, D. (Updated 2011 February 17). CPK isoenzymes test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003504.htm. Accessed December 2012.
Schreiber, D. and Miller, S. (Updated 2011 March 29). Use of Cardiac Markers in the Emergency Department. [On-line information]. Available online at http://emedicine.medscape.com/article/811905-overview through http://emedicine.medscape.com. Accessed December 2012.
Domanski, M. (2012 December 03). Prognostic Implications of Troponin T and Creatine Kinase, MB Elevation After Coronary Artery Bypass Grafting. Medscape Today News from Am Heart J. v 164(5):636-637. [On-line information]. Available online at http://www.medscape.com/viewarticle/774259 through http://www.medscape.com. Accessed December 2012.
(© 1995-2012). Creatine Kinase (CK) MB Isoenzyme, Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/82429 through http://www.mayomedicallaboratories.com. Accessed December 2012.
Lehman, C. and Meikle, A. (Updated 2012 November). Ischemic Heart Disease. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/IHD.html?client_ID=LTD through http://www.arupconsult.com. Accessed December 2012.
Pagana, K. D. & Pagana, T. J. (© 2011). Mosby's Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 322-325.
Clarke, W., Editor (© 2011). Contemporary Practice in Clinical Chemistry 2nd Edition: AACC Press, Washington, DC. Pp 300-303.
McPherson, R. and Pincus, M. (© 2011). Henry's Clinical Diagnosis and Management by Laboratory Methods 22nd Edition: Elsevier Saunders, Philadelphia, PA. Pp 489.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp. 312-315.
Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER and Bruns DE, eds. 4th ed. St. Louis, Missouri: Elsevier Saunders; 2006. P. 599.
Engel G, Rockson SG. Rapid diagnosis of myocardial injury with troponin T and CK-MB relative index. Mol Diagn Ther. 2007;11(2): 109-16. Available online through http://www.ncbi.nlm.nih.gov/pubmed. Accessed February 2009.
Innotrac Diagnsostics. CK-MB Kit. Available online at http://www.innotrac.fi/index.php?main=products§ion=cardiac&subsection=ckmb through http://www.innotrac.fi. Accessed February 2009.