What is a B-type natriuretic peptide (BNP) test?

A B-type natriuretic peptide (BNP) test is a blood test. It measures the levels of a certain type of hormone in your blood called a B-type natriuretic peptide. This test gives your healthcare provider information about your heart.

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Higher-than-normal levels of BNP in your blood can be a sign that your heart isn’t working as it should. It can mean that your heart isn’t pumping enough blood through your body. Since BNP is cleared by your kidneys, it may also mean that your kidneys are not functioning properly.

Some laboratories offer a similar test called “aminoterminal pro B-type natriuretic peptide” (or NT-proBNP). Both the BNP and NT-proBNP tests show similar information, although the absolute values of NT-proBNP are about five to 10 times higher than BNP.

Providers use a BNP or an NT-proBNP test to diagnose heart failure. If you already know you have heart failure, your provider may order this test to check the severity (seriousness) of your condition. They may also use this test to monitor how heart failure treatments are working. In some cases, your provider may also order it if they think you may be at higher risk of developing heart failure.

Your provider orders this test to look for higher levels of BNP in your blood to check for cardiovascular disease. You may get a BNP or NT-proBNP test if you have symptoms of heart failure.

Symptoms of heart failure include:

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Heart failure means your heart isn’t pumping blood as it should. It doesn’t mean that your heart has failed or stopped working entirely. If your provider has already diagnosed you with heart failure, they may order a BNP or NT-proBNP test to monitor how treatments are working.

Get emergency medical help if you have these symptoms. Heart failure is life-threatening and requires immediate treatment.

BNP is one of several proteins that help regulate blood circulation throughout your body. Even though your heart makes this protein, providers sometimes call it “brain” natriuretic peptide because it was first discovered in brain tissue.

As part of your circulatory system, your heart and blood vessels pump oxygen-rich blood to your muscles, organs and other tissues. The left ventricle (one of the heart’s four chambers) pumps a great deal of blood through the heart and it goes on to flow through your body.

The left ventricle is one of the main organs that make BNP. As your heart stretches due to increasing load or experiences increased stress from injury, BNP levels rise. Your heart muscle cells respond to such stress by secreting BNP to unload your heart, which prompts your kidneys to relieve salt and water (hence the name “natriuretic”).