Troponin and Cardiac Markers on the NCLEX
Troponin sensitivity and timing, CK-MB legacy, BNP for HF.
Cardiac markers distinguish MI and HF. NCLEX tests troponin timing and BNP for HF.
Troponin
Most sensitive and specific for MI. Elevates 3-6h after injury. Peaks 12-24h. Stays elevated 7-10 days. High-sensitivity troponin (hs-cTn) detects smaller injury earlier.
CK-MB
Older marker. Peaks 12-24h. Returns to normal 2-3 days. Largely replaced by troponin.
BNP
B-type natriuretic peptide, released by ventricles under stretch. Elevated in HF. >100 suggests HF; higher = more severe. NT-proBNP similar info.
False elevations
Troponin can rise from renal failure, sepsis, PE, myocarditis, demand ischemia. BNP rises in renal failure.
Frequently asked
Negative troponin, rules out MI?
Serial troponins 3-6h apart. Single normal at presentation insufficient.
BNP after diuresis?
Falls. Useful to track HF response.
Quick check
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