Brain Natriuretic Peptide (BNP) Test: About This Test

What is a BNP test?

A brain natriuretic peptide (BNP) test measures the amount of the BNP hormone in your blood. BNP is made by your heart. It can help show 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. This increases the blood level of BNP.

Your doctor will use your physical exam and other tests along with your BNP level to check your heart. Sometimes a related substance called NT-proBNP may be measured. The results provide information similar to the BNP test.

Why is the test 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 is the test done?

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

How do you prepare?

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

What do the results of the test mean?

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 exam to find out for sure if you have heart failure.