- N-terminal (NT)-pro hormone BNP (NT-proBNP) is a non-active prohormone that is released from the same molecule that produces BNP. - B-type natriuretic peptide (BNP) is a hormone produced by your heart.- Both BNP and NT-proBNP are released in response to changes in pressure inside the heart.These changes can be related to heart failure and other cardiac problems..