NT-proBNP
N-terminal pro-brain natriuretic peptide — an inactive fragment released alongside BNP from cardiac ventricles under stress. NT-proBNP is a widely used blood test for diagnosing and monitoring heart failure. Elevated levels indicate increased cardiac wall stress. It has a longer half-life than BNP, making it easier to measure.
Technical Context
NT-proBNP is produced 1:1 with BNP from proBNP cleavage but has a longer half-life (~120 min vs ~20 min for BNP) and higher circulating concentrations, making it easier to measure reliably. Age-stratified rule-out cutoffs for acute heart failure (ESC guidelines): <50 years: <450 pg/mL; 50-75 years: <900 pg/mL; >75 years: <1800 pg/mL. Single rule-out cutoff: <300 pg/mL (high negative predictive value ~98%). Elevated NT-proBNP also occurs in: renal impairment (reduced clearance), pulmonary embolism, sepsis, critical illness, and atrial fibrillation. For peptide drug trials: NT-proBNP is increasingly used as a safety biomarker (detecting subclinical cardiac effects) and as an inclusion/stratification criterion for cardiovascular outcome trials. The SELECT trial (semaglutide 2.4mg for cardiovascular risk reduction) used NT-proBNP as a biomarker of cardiac risk.