TruQuick™ MYO/CK/cTnI Combo

Myoglobin (MYO), Creatine Kinase MB (CK-MB) and cardiac Troponin I (cTnI) are proteins released into the bloodstream after cardiac injury. Myoglobin is a heme-protein normally found in skeletal and cardiac muscle with a molecular weight of 17.8 kDa.1 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 two to four hours post-infarct, peaking at nine to 12 hours, and returning to baseline within 24-36 hours.2, 3 CK-MB is an enzyme also present in the cardiac muscle, with a molecular weight of 87.0 kDa.4 Creatine Kinase is a dimeric molecule formed from two subunits designated as “M” and “B”, which combine to form three different isoenzymes, CKMM, CK-BB and CK-MB. CK-MB is the isoenzyme of Creatine Kinase most involved in the metabolism of cardiac muscle tissue.5 The release of CK-MB into the blood following an MI can be detected within three to eight hours after the onset of symptoms. It peaks within nine to 30 hours, and returns to baseline levels within 48 to 72 hours.6 Cardiac Troponin I is a protein found in cardiac muscle, with a molecular weight of 22.5 kDa.7 Troponin I is part of a three subunit complex comprised 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.8 After cardiac injury occurs, Troponin I is released into the blood four to six hours after the onset of pain. The release pattern of Troponin I is similar to CK-MB, but while CK-MB levels return to normal after 72 hours, Troponin I remains elevated for six to 10 days, thus providing for a longer window of detection for cardiac injury.