Natriuretic peptides

Brain natriuretic peptide, also called B-type natriuretic peptide (BNP), is a protein that your heart and blood vessels make. BNP helps your body eliminate fluids, relaxes blood vessels and moves sodium into your urine.

When your heart is damaged, your body secretes high levels of BNP into your bloodstream to try to ease the strain on your heart. One of the most important uses of BNP is to try to determine whether shortness of breath is due to heart failure.

Normal BNP levels vary according to age and gender and whether you are overweight. For people who have heart failure, establishing a baseline BNP can be helpful and future tests can be used to help measure how well treatment works.

A variation of BNP called N-terminal BNP is also useful for diagnosing heart failure and for evaluating the risk of a heart attack and other problems in those with existing heart disease.

A high level of BNP alone isn't enough to diagnose a heart problem. Your doctor will also consider your risk factors and other blood test results.