The NT-proBNP Assay Kit provides the assay-specific components for the quantitative determination of N-terminal pro-brain (or B-type) natriuretic peptide (NT-proBNP). NT-proBNP is produced predominantly by cardiac ventricular myocytes. It is released in response to volume expansion and filling pressure and is involved in maintaining intravascular volume homeostasis. Elevated plasma levels of BNP and NT-proBNP have been observed at times of cardiac stress and damage.