Content Map Terms

Brain Natriuretic Peptide (BNP) Test

Test Overview

A brain natriuretic peptide (BNP) test measures the amount of the BNP hormone in your blood. BNP is made by your heart and shows how well your heart is working. Normally, only a low amount of BNP is found in your blood. But if your heart has to work harder than usual over a long period of time, such as from heart failure, the heart releases more BNP, increasing the blood level of BNP.

Why It Is Done

The BNP test is used to:

  • Check to see if you have heart failure. A doctor may think that you have heart failure if you are having problems such as trouble breathing or swelling in your legs.
  • Find out how severe heart failure is.

How To Prepare

You do not need to do anything before you have this test.

How It Is Done

A health professional uses a needle to take a blood sample, usually from the arm.

How It Feels

When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.


There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.


Normal BNP values are higher in women than in men. BNP values normally increase with age. But they may stay within a normal range unless you have heart failure.

Your doctor will discuss your results with you. A normal BNP level means that you probably don't have heart failure. A higher-than-normal BNP level means that you might have heart failure. A very high BNP level means that heart failure is much more likely.

Your doctor will also look at other tests and your physical examination to find out for sure if you have heart failure.


Current as of: September 7, 2022

Author: Healthwise Staff
Medical Review:
E. Gregory Thompson MD - Internal Medicine
Martin J. Gabica MD - Family Medicine
Adam Husney MD - Family Medicine
Stephen Fort MD, MRCP, FRCPC - Interventional Cardiology