Brain natriuretic peptide (BNP) circulates in blood as a peptide hormone with natriuretic, vasodilatory and renin inhibitory properties. BNP is secreted predominantly by the left ventricular myocytes in response to volume expansion and pressure overload. BNP belongs to a family of structurally similar peptide hormones, which includes atrial natriuretic peptide (ANP), BNP, C type natriuretic peptide (CNP) and urodilatin.