peptide bnp FAQ

When you have heart failure, your heart makes more B-type natriuretic peptide (BNP) and N-terminal-proBNP (NT-proBNP). Levels of both go up in your blood when your heart failure gets worse and go down when it gets better. A BNP test measures your blood level of BNP. Sometimes, doctors might order a test that measures levels of NT-proBNP instead. Both tests tell you about the same thing. Doctors can use them to help diagnose or rule out heart failure when you have symptoms. They're able to spot heart failure more than 80% of the time. If you already have heart failure, your doctor might also use one of these blood tests to see how your heart is doing and if your condition is getting better, worse, or staying the same. These tests can also help you find out if any treatments you're taking for heart failure are working or not.

BNP is a peptide (a short chain of amino acids) your heart and blood vessels make. It works as a hormone. That means it sends messages through your blood to other cells or organs in your body. Your heart makes BNP normally. Your heart will make more of it when it's working harder than it should to pump and move blood through your body. When your blood vessels get the signal from BNP, it tells them to open up more to lower blood pressure and make it easier for your heart to pump your blood. The hormone also tells your kidneys to filter out more water and salt and get rid of it in your pee. Getting rid of water and salt is one way your body lowers blood pressure to make things easier on your heart. BNP and a closely related peptide (called NT-proBNP for short) go by a few different names. These include:

BNP levels can help your doctor figure out if you have heart failure or something else that has similar symptoms, including shortness of breath. The test can also show if your heart failure has gotten worse. It’ll help your doctor decide what treatments you need and if you need to go to the hospital. It may also give them a look into what the future may hold for you. It's a sensitive test that allows your doctor to see if your heart failure is better or worse and whether or not your medicine is working well for you. Depending on your medical center, your doctor may order tests for one or both peptides. They may order it when you have signs that might be heart failure or when you are being treated for heart failure. Signs of heart failure that may warrant a BNP test include:

You don't need to do anything special to get ready to have a BNP test. A small amount of blood will be taken from you, using a small needle. It might sting or hurt a little bit when the needle goes into your arm or comes back out. But it shouldn't hurt a lot like any blood test. This part shouldn't take more than about 5 minutes. Sometimes, you might get tested using a finger stick instead of drawing a vial full of blood. You're more likely to have this type if you're in the hospital as opposed to a clinic or doctor's office. It's possible to test your levels with just a few drops of blood. They'll put your sample in a machine that measures how much BNP or NT-pro-BNP is in your blood. The test usually takes about 15 minutes to run. In some places, your blood sample may have to go to another lab for testing. After they draw your blood, they'll put a bandage on your arm. You might notice a little soreness or a bruise later. But there aren't any serious risks from having a BNP blood test.

BNP tests, also called a B-type natriuretic peptide test, measure BNP by picograms (pg) per milliliter (mL) or nanograms per liter. The range includes:

When you have symptoms of heart failure, such as fatigue and shortness of breath, a BNP test can help your doctor determine whether it’s heart failure or pneumonia. The BNP test is particularly useful in distinguishing heart failure from other potential causes of these symptoms. BNP blood tests lead to an accurate diagnosis of heart failure about 90% of the time, making it a critical tool in the diagnostic process. BNP levels can also help your doctor determine your outlook after heart failure. Generally, a higher level means a worse outcome. As BNP levels drop, however, you’ll start to feel better and breathe easier, and your outlook will get better, too. This improvement in BNP levels correlates with a better prognosis, as the heart begins to stabilize and recover. After diagnosis, additional BNP tests can:

Low BNP levels mean you likely don’t have heart failure. Your doctor can rule that diagnosis out and look at other reasons why you may have symptoms such as shortness of breath. Low BNP levels help exclude heart failure, as low levels typically indicate that the heart is not under significant stress. This can help narrow down the causes of your symptoms, guiding your health care provider toward the correct diagnosis. High BNP levels mean that your doctor may make a diagnosis of heart failure. Also, levels are higher when heart failure is worse, and they go down when the heart is stable. Monitoring BNP levels over time can provide valuable insights into how well the heart is responding to therapy. If you have high BNP levels but the doctor rules out heart failure, the levels may point to other conditions such as: