Troponin I/Myoglobin/CK-MB Rapid Test

Background of Clinical Indications

Cardiac Troponin I, Myoglobin and Creatine Kinase MB are proteins released into the blood stream after cardiac injury. Cardiac Troponin I is a cardiac muscle protein with a molecular weight of 22.5 kilodalton.1 Troponin I is part of a three subunit complex comprising of Troponin T and Troponin C. Along with tropomyosin, this structural complex forms the main component that regulates the calcium sensitive ATPase activity of actomyosin in striated skeletal and cardiac muscle.2 After cardiac injury occurs, Troponin I is released into the blood 4-6 hours after the onset of pain. The release pattern of cTnI is similar to CK-MB, but while CK-MB levels return to normal after 72 hours, Troponin I remains elevated for 6-10 days, thus providing for a longer window of detection for cardiac injury. Myoglobin is a hemeprotein normally found in skeletal and cardiac muscle with a molecular weight of 17.8 kDa. It constitutes about 2 percent of total muscle protein and is responsible for transporting oxygen within muscle cells.3 When muscle cells are damaged, Myoglobin is released into the blood rapidly due to its relatively small size. The level of Myoglobin increases measurably above baseline within 2-4 hours post-infarct, peaking at 9-12 hours, and returning to baseline within 24-36 hours.4,5 CK-MB is an enzyme also present in the cardiac muscle, with a molecular weight of 87.0 kDa.6 Creatine Kinase is a dimeric molecule formed from two subunits designated as “M” and “B”, which combine to form three different isoenzymes, CK-MM, CK-BB and CK-MB. CK-MB is the isoenzyme of Creatine Kinase most involved in the metabolism of cardiac muscle tissue.7 The release of CK-MB into the blood following an MI can be detected within 3-8 hours after the onset of symptoms. It peaks within 9 to 30 hours, and returns to baseline levels within 48 to 72 hours.8 The Troponin I/Myoglobin/CK-MB Rapid Test utilizes a combination of antibody coated particles and capture reagents to qualitatively detect Troponin I, Myoglobin and CK-MB in human whole blood, serum or plasma specimens. The minimum detection level is 1.0 ng/mL Troponin I,50 ng/mL Myoglobin and 5.0 ng/mL CK-MB.