Question

3. Explain the following enzymes and their role in acute myocardial infarction. Compare sensitivity and specificity and tell pros and cons of using each as diagnostic tool. a. Troponin 1 b. Creatinine kinase-Myocardial Bands (CKMB) c. Myoglobin

Answer 1

Troponin I:
Troponin I is a group of proteins that helps the heart muscle to regulate its contraction. When there is a high level of protein that causes the cardiac disorder. The high troponin level indicates cardiac injury. It is equally sensitive and more specific to myocardial infarction. The troponin test detects the level of cardiac-specific troponin in the blood that causes MI. A high sensitivity test may be positive in stable angina with no symptoms. It becomes elevated in MI within 3 to 4 hours and remains in high for 10 to 14 days. High sensitivity troponin test detects a low level of troponin I. Troponin I sometimes ordered with CK-MB, than CK-MB troponin I is more specific for heart injury. Troponin I provide correct diagnoses for MI. Troponin I is a greater specific for MI than others and the main drawback of this troponin I is higher sensitivity interferes with the low level of high sensitivity elevation in unstable angina, chronic renal failure. It remains elevated for a longer period in acute coronary events.
CK-MB:
It is a cardiac biomarker, it is an enzyme found in heart muscle cells. A high level of CK-MB indicates a heart attack. based on activity measures it is more sensitive in 12 to 24 intervals comparing the sensitivity of cardiac troponin I. elevated CK-MB is highly specific and sensitive for myocardial injury. It has cross-reactivity with other isoforms and makes false-positive results.
Myoglobin:
It is an oxygen-binding protein is found in muscle. It is an early indication for acute myocardial infarction. myoglobin level remains elevated for one hour after MI and it reaches a peak level within 4 to 6 hours. The specificity of myoglobin lower than Ck-MB it has high sensitivity and high predictive value for MI. It is not specific for acute MI. it is a biomarker present in the heart and skeletal muscle it identifies acute MI and fastly elevated in unrelated acute Myocardial infarction in skeletal and neuromuscular disorder.