B-Type Natriuretic Peptide (BNP) Test

A B-type natriuretic peptide (BNP) test is a blood test that helps diagnose heart failure. B-type natriuretic peptide is a protein that your heart makes. But providers sometimes call it “brain” natriuretic peptide. This is because scientists first discovered it in brain tissue. BNP helps manage blood flow.

Higher-than-normal levels of BNP can be a sign that your heart isn’t pumping enough blood through your body.

Some laboratories offer a similar test called “aminoterminal pro B-type natriuretic peptide” (or NT-proBNP). Both tests provide similar information. But their normal ranges are different.

Your healthcare provider may do a BNP or NT-proBNP test:

• If you have symptoms of heart failure, like shortness of breath and fatigue
• To check the severity of heart failure if you already have it
• To see if your treatment plan is working
• To check on your heart health if you’re at increased risk for heart failure

What is BNP?

BNP is one of several proteins that help manage how your blood flows throughout your body. Your heart (especially the left ventricle) makes this protein. NT-proBNP is like an ingredient that turns into BNP.

As your heart works harder and stretches, it releases more BNP. BNP prompts your kidneys to get rid of more salt and water through your pee. It also tells your blood vessels to open. These actions result in lower blood pressure and less blood. So, your heart doesn’t have to work as hard.

BNP is necessary in certain situations. But high levels of it signal that your heart isn’t working as it should. This often means you have heart failure. However, other health conditions can affect your BNP levels.

What should I expect during the test?

A healthcare provider will clean your arm and insert a needle into a vein. They’ll remove some of your blood. The needle may pinch or sting when it goes in.

After taking a blood sample, the provider will place a bandage on your arm. The area may be a little sore. You may have a small bruise.

A lab will examine your blood and check the levels of BNP or NT-proBNP.

When should I know the results of the test?

You’ll probably get your results right away, usually in under 15 minutes. This is because healthcare providers often do this test in the emergency room when you’re having symptoms of heart failure.

If you already have a heart failure diagnosis, it may take one to two days to get the results.

What is the normal range for a BNP test?

In general, normal BNP levels are less than 100 picograms per milliliter (pg/mL).

For NT-proBNP, normal levels are:

• Less than 125 pg/mL if you’re under 75 years old
• Less than 450 pg/mL if you’re over 75 years old

Certain factors may affect what’s normal for you. For example, having obesity can lower your BNP level. Your healthcare provider will consider your medical history when interpreting your results.

What do the results mean?

BNP levels over 100 pg/mL and NT-proBNP levels over 900 pg/mL may be signs of heart failure. Your healthcare provider will need to do other tests to confirm the diagnosis.

In general, the higher the level, the more serious heart failure may be. But other factors can increase these levels, including:

• Chronic kidney disease
• Other types of heart disease
• Certain lung conditions, like a blood clot in your lung and high blood pressure in your lungs

If the results are abnormal, what are the next steps?

Your healthcare provider may recommend other tests, like an electrocardiogram (EKG). It can help your provider diagnose or evaluate heart failure and other heart problems.