Testsealabs Myoglobin/CK-MB/Troponin ⅠCombo Test

Myoglobin (MYO) is a heme-protein 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 the muscle cells. When the muscle cells are damaged, myoglobin is released into the blood rapidly due to its relatively small size.

Following the death of tissue associated with myocardial infarction (MI), myoglobin is one of the first markers to rise above normal levels. 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. A number of reports suggest the measurement of myoglobin as a diagnostic aid in confirming the absence of myocardial infarction, with negative predictive values reported at certain time periods after onset of symptoms.

Creatine kinase MB (CK-MB) is an enzyme present in the cardiac muscle with a molecular weight of 87.0 kDa. 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.

The release of CK-MB into the blood following 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. CK-MB is one of the most important cardiac markers and is widely recognized as the traditional marker for the diagnosis of MI.

Cardiac troponin I (cTnI) is a protein found in cardiac muscle with a molecular weight of 22.5 kDa¹. Troponin I is part of a three-subunit complex comprising 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.

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 a longer window of detection for cardiac injury.

The high specificity of cTnI measurements for the identification of myocardial damage has been demonstrated in conditions such as the perioperative period, after marathon runs, and blunt chest trauma. cTnI release has also been documented in cardiac conditions other than acute myocardial infarction (AMI), such as unstable angina, congestive heart failure, and ischemic damage due to coronary artery bypass surgery. Because of its high specificity and sensitivity in myocardial tissue, troponin I has recently become the most preferred biomarker for myocardial infarction.

The Myoglobin/CK-MB/Troponin I Combo Test is a simple test that utilizes a combination of MYO/CK-MB/cTnI antibody-coated particles and capture reagent to selectively detect MYO/CK-MB/cTnI in whole blood/serum/plasma.