cTnI-Myo-CKMB 3-in-1 Test

Cat.No.CTNI 722


For simultaneous qualitative determination of myoglobin (Myo), creatine kinase MB (CK-MB), and troponin I (cTnI) in human plasma or serum as an aid in the diagnosis of acute myocardial infarction in emergency room, critical care, point-of-care and hospital settings. 
The Myo/CK-MB/cTnI Test provides a qualitative analytical test result. The qualitative nature of this assay does not provide information about any change - either the rise or fall - in the concentration of myoglobin, CK-MB, and cardiac troponin I with single testing. A quantitative method should be used, if desired, to quantitate the concentration of Myo, CK-MB and cTnI at any given time. Only with serial testing could a temporal change in the level of Myo, CK-MB, and cTnI be concluded. Clinical consideration and professional judgment should be applied when interpreting the results of the Myo/CK-MB/cTnI test, especially when a single test result is used.


Myo, CK-MB and cTnI are proteins found in cardiac muscle cells and are released into the blood upon damage or death of cardiac tissue. 
Myoglobin is an oxygen-binding heme protein with a molecular weight of 17,800 daltons, normally found in skeletal as well as cardiac tissue. It constitutes about 2% of the total muscle protein and is located in the cytoplasm of cells. 
Also found in the cytoplasm is creatine kinase. CK catalyzes the reversible phosphorylation reaction of creatine with ATP. In humans, isoenzymes of CK have been identified in both the cytosol and mitochondria of cells from a wide variety of tissues. Cytosolic CK exists as a dimeric molecule formed from two types of single-polypeptide subunits, designated “M” and “B”. Each subunit has a molecular weight of approximately 41,000 daltons and distinct immunologic epitopes. These two subunits combine to form three different isoenzymes of CK: CK-MM, CK-BB, CK-MB. The relative abundance of the particular isoenzyme is dependent on the tissue being examined. The CK-MM isoenzyme is predominant in skeletal muscle tissue, while the CK-MB isoenzyme is most abundant in cardiac muscle tissue. 
cTnI is part of the troponin complex which, together with tropomyosin, forms the main component that regulates the Ca++-sensitive ATPase activity of actomyosin in striated muscle (skeletal and cardiac). The troponin complex consists of three subunits, troponin T (TnT), troponin I (TnI), and troponin C (TnC). Each subunit has a distinct function with TnC as the site of Ca++ binding, TnT the tropomyosin binding, and TnI as the inhibitory subunit. Different isoforms of TnI exist in the skeletal and cardiac muscles (sTnI and cTnI, respectively) with distinct immunologic epitopes that allow the production of cardiac-specific TnI antibodies.
The cardiac markers myoglobin, CK-MB, and troponin I have been established as useful tools in the diagnosis of acute myocardial infarction (AMI). Since the temporal release patterns of the three markers have significant differences, all three are useful tools in the determination of the source and timing of the onset of chest pain. Cell injury from AMI has been shown to result in a level of blood myoglobin above the upper limit of normal in approximately 2-3 hours after the onset of chest pain. Maximum concentrations are generally observed after 9-12 hours. CK-MB and troponin I are found in blood at elevated concentrations approximately 4- 6 hours after the onset of chest pain and peak at 12-24 hours. However, whereas CK-MB levels return to normal values in about 72 hours, troponin I levels remain elevated for up to 5-7 days. The use of these three markers is therefore complementary since they detect cardiac tissue damage over a wide range of times after myocardial infarction.

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CTNI 722
cTnI-Myo-CKMB 3-in-1 Test