Ask An Expert: BNP Test

Content provided by the Faculty of the Harvard Medical School

Ask An Expert: BNP Test

Question:

My father had a blood test called a "BNP." The results showed the possibility of some type of heart failure. What is a BNP test?

Answer:

BNP stands for "B-type natriuretic peptide," which is a chemical that is released by the walls of the heart when it is under unusual stress — as is often the case for patients with heart failure. In heart failure, the heart cannot pump as much blood as the body needs, and the pressure of blood trying to enter the heart tends to build up. This high "filling pressure" stretches the walls of the heart, which releases BNP as a kind of biological call for help.

BNP helps dilate blood vessels, making it easier for the heart to do its work by lowering the resistance against which it pumps. It also helps the kidneys increase urine formation, which decreases the pressure of blood filling the heart.

Your father had a test showing higher than usual levels of BNP, which probably means that his heart muscle is under this kind of strain. Studies have shown that higher BNP levels mean a greater risk for heart failure, and a higher risk for heart complications.

Thomas Lee, M.D., is the chief executive officer for Partners Community HealthCare Inc. He is a professor of medicine at Harvard Medical School. He is an internist and cardiologist at Brigham and Women's Hospital. Dr. Lee is the chairman of the Cardiovascular Measurement Assessment Panel of the National Committee for Quality Assurance.

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Last updated:	January 24, 2007

Medical content reviewed by the Faculty of the Harvard Medical School. Harvard Health Publications, Copyright © 2007 by President and Fellows of Harvard College. All rights reserved. Used with permission of StayWell.

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