The B-type natriuretic peptide, also known as BNP, and N-terminal pro-b-type natriuretic peptide, also known as NTproBNP, are peptides (proteins which are smaller in size) which either function as hormones or are part of a peptide that once had some hormones in its composition. These peptides are produced in the body by the heart in small quantities during normal functioning. They are released in higher quantities by the heart when it senses that it needs to work harder. This chain of action supports volume expansion as well fluid retention in the vein and the arteries. Afterward, when the heart is in a resting condition, the heart muscle is stretched and has to work harder to pump the blood around the body. The tests for BNP and Nt-proBNP are used to measure the levels of these peptides in the blood and evaluate heart failure. The two tests are used for different purposes and are not interchangeable. In addition, they must not be used together. The doctor must order either one of the tests but not both. Moreover, the nuances of the term heart failure must be learned. The term heart failure does not imply that the heart fails to supply blood around the body; it simply implies that the heart has difficulty in supplying it. Healthcare practitioners have several approaches towards the treatment of heart failure. The approach chosen by your doctor is contingent on the severity of the disease. BNP is produced primarily by the cells present in the left ventricle of the heart. Initially, it was called brain natriuretic peptide as it was found in the brain tissue. The left ventricle of the heart functions as the main blood-pumping chamber, and it transports oxygenated blood from the lungs to the rest of the organs in the body. The peptides found in the left ventricle are also associated with blood pressure and volume and the work that the heart puts in to supply the blood to the rest of the body. There are small amounts of the precursor protein, also known as pro-BNP, produced by the heart continuously. The peptide is then split by an enzyme called CORIN in order to release the active hormone BNP and NT-proBNP
, an inactive fragment into the blood. In the event that the heart is experiencing heart failure – when the left ventricle of the heart is having a hard time pumping oxygenated blood around the body in ample amounts – the concentration of these peptides, BNP and NT-proBNP, rise by large margins. This is a common occurrence with diseases and conditions which afflict the circulatory system and the heart. The high levels of circulating BNP and NT-proBNP indicate the diminished capacity of the left ventricle to supply oxygenated blood around the body.