Which laboratory tests confirm the diagnosis of myocardial infarction?

Which laboratory tests confirm the diagnosis of myocardial infarction?

• A. PT, PTT, INR
• B. Troponin, CK-MB, LDH
• C. Na+, K+, CK-BB
• D. BUN, Cr, CK-MM

Answer: (B)

The main idea is that confirming a myocardial infarction relies on cardiac biomarkers that indicate heart muscle injury. The strongest and most specific signal comes from troponin (I or T), which rises within a few hours of injury and remains elevated for days. CK-MB is another marker that rises a bit later than troponin and falls back toward normal within a couple of days, helping confirm acute injury and detect possible reinfarction when serial measurements are compared. LDH also rises after myocardial damage, though it is less specific than troponin and is used less frequently today. When these biomarkers are elevated in the context of chest pain and typical ECG changes, they confirm myocardial infarction. Coagulation tests (PT, PTT, INR) assess bleeding and clotting function, not myocardial injury. Electrolytes (Na+, K+) and CK-BB (brain isoenzyme) are not diagnostic for MI. BUN, creatinine gauge kidney function, and CK-MM reflects skeletal muscle, not heart muscle.

The main idea is that confirming a myocardial infarction relies on cardiac biomarkers that indicate heart muscle injury. The strongest and most specific signal comes from troponin (I or T), which rises within a few hours of injury and remains elevated for days. CK-MB is another marker that rises a bit later than troponin and falls back toward normal within a couple of days, helping confirm acute injury and detect possible reinfarction when serial measurements are compared. LDH also rises after myocardial damage, though it is less specific than troponin and is used less frequently today. When these biomarkers are elevated in the context of chest pain and typical ECG changes, they confirm myocardial infarction.

Coagulation tests (PT, PTT, INR) assess bleeding and clotting function, not myocardial injury. Electrolytes (Na+, K+) and CK-BB (brain isoenzyme) are not diagnostic for MI. BUN, creatinine gauge kidney function, and CK-MM reflects skeletal muscle, not heart muscle.