CPK-MB test

{{Short description|Cardiac marker}}

{{Infobox diagnostic

| Name = CPK-MB test

| Image = AMI bloodtests engl.png

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| Caption = Kinetics of cardiac markers in myocardial infarction with or without reperfusion treatment

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| LOINC = {{LOINC|49551-5}}, {{LOINC|51506-4}}, {{LOINC|2154-3}}, {{LOINC|13969-1}}, {{LOINC|32673-6}}, {{LOINC|38482-6}}

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| Reference_range = 2 to 19.5 U/L (at 37 C in adults),{{Cite web |title=CREATINE KINASE – MB CK-MB LQ |url=https://atlas-medical.com/upload/productFiles/208011/PPI1629A01%20CK-MB%20LIQUID%20Rev%20A.pdf}}
some places 5 to 25 IU/L{{Citation |last=Cabaniss |first=C. Daniel |title=Creatine Kinase |date=1990 |url=http://www.ncbi.nlm.nih.gov/books/NBK352/ |work=Clinical Methods: The History, Physical, and Laboratory Examinations |editor-last=Walker |editor-first=H. Kenneth |edition=3rd |place=Boston |publisher=Butterworths |isbn=978-0-409-90077-4 |pmid=21250193 |access-date=2022-04-18 |editor2-last=Hall |editor2-first=W. Dallas |editor3-last=Hurst |editor3-first=J. Willis}}

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The CPK-MB test (creatine phosphokinase-MB), also known as CK-MB test, is a cardiac marker{{cite journal |author=Guzy PM |title=Creatine phosphokinase-MB (CPK-MB) and the diagnosis of myocardial infarction |journal=West. J. Med. |volume=127 |issue=6 |pages=455–60 |date=December 1977 |pmid=339548 |pmc=1237914 }} used to assist diagnoses of an acute myocardial infarction, myocardial ischemia, or myocarditis. It measures the blood level of CK-MB (creatine kinase myocardial band), the bound combination of two variants (isoenzymes CKM and CKB) of the enzyme phosphocreatine kinase.{{cn|date=April 2022}}

In some locations, the test has been superseded by the troponin test. However, recently, there have been improvements to the test that involve measuring the ratio of the CK-MB1 and CK-MB2 isoforms.{{cite web |url=http://emedicine.medscape.com/article/811905-overview |title=Use of Cardiac Markers in the Emergency Department: - eMedicine |accessdate=2009-01-10}}

The newer test detects different isoforms of the B subunit specific to the myocardium whereas the older test detected the presence of cardiac-related isoenzyme dimers.{{cn|date=March 2021}}

Many cases of CK-MB levels exceeding the blood level of total CK have been reported, especially in newborns with cardiac malformations, especially ventricular septal defects. This reversal of ratios is in favor of pulmonary emboli or vasculitis. An autoimmune reaction creating a complex molecule of CK and IgG should be taken into consideration.{{cite journal |author1=Boucek RJ Jr |author2=Kasselberg AG |author3=Boerth RC |author4=Parrish MD |author5=Graham TP Jr |title=Myocardial injury in infants with congenital heart disease: evaluation by creatine kinase MB isoenzyme analysis |journal=Am J Cardiol |volume=50 |issue=1 |pages=129–35 |date=July 1982 |pmid=7090995 |doi= 10.1016/0002-9149(82)90018-2}}

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