Brain Natriuretic Peptide (BNP)
A peptide hormone released by cardiac ventricular cells in response to increased wall stress. BNP and its inactive fragment NT-proBNP are widely used as blood test biomarkers for diagnosing and monitoring heart failure. Despite its name, BNP's primary clinical significance relates to cardiac rather than brain function.
Technical Context
Despite its name, BNP's primary clinical significance relates to the heart. ProBNP (108 aa) is constitutively produced by ventricular cardiomyocytes and cleaved upon release to active BNP (32 aa, half-life ~20 minutes) and inactive NT-proBNP (76 aa, half-life ~120 minutes). Both are elevated in heart failure proportional to wall stress/severity. NT-proBNP is preferred for clinical testing due to its longer half-life and greater stability. Clinical cutoffs: NT-proBNP <300 pg/mL effectively rules out acute heart failure (high negative predictive value). Age-stratified cutoffs are used for diagnosis. BNP/NT-proBNP levels are used in heart failure diagnosis, prognosis, and treatment monitoring, and are sometimes included as secondary endpoints in cardiovascular outcomes trials for metabolic peptide drugs.