B-type natriuretic peptide (BNP) is a cardiac neurohormone specifically secreted from the ventricles in response to volume expansion and pressure overload. The actions of BNP include natriuresis, diuresis, vasorelaxation, and inhibition of renin and aldosterone secretion. It is also found to help restore the body's salt and water balance and improve heart function. BNP is co-secreted along with a biologically inactive N-terminal fragment (NT-proBNP). Circulating BNP and NT-proBNP provide important information on cardiac dysfunction, hypervolemia, and risk in patients with severe impairment of kidney function.