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BNP (Blood)

Does this test have other names?

B-type natriuretic peptide

What is this test?

This test looks for the hormone BNP in your blood. BNP stands for brain natriuretic peptide. It is made inside the pumping chambers of your heart when pressure builds up from heart failure. The test is an important tool for healthcare providers to diagnose heart failure quickly.

Heart failure occurs when your heart is not pumping blood well. This causes cells inside your heart to release BNP. This opens up blood vessels in your body to take pressure off your heart. A BNP blood test correctly shows heart failure about 90% of the time.

The BNP test can help your healthcare provider diagnose heart failure, plan treatment, see how well the treatment is working, and figure out when it is safe for you to leave the hospital. The BNP test can show how serious your heart failure is now and how severe your heart failure will be in the future. A BNP test is quite accurate and it only takes about 15 minutes to get the results. 

Why do I need this test?

You may need this test if your healthcare provider suspects that you have heart failure.

The main symptom of heart failure is difficulty breathing (dyspnea). If you go to your provider's office or the emergency room with trouble breathing, your provider will want to know the cause as quickly as possible. Many conditions can cause breathing difficulties, but if you also have a blood test that is positive for BNP, heart failure is likely causing your symptoms.

You may also need this test so that your healthcare provider can see how well your heart failure therapy is working. 

What other tests might I have along with this test?

You may have a blood test called atrial natriuretic peptide (ANP). ANP is a hormone similar to BNP, but it is made in a different part of the heart. You may also have other blood tests, a chest X-ray, an electrocardiogram, or an echocardiogram, which is an ultrasound of the heart. 

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your healthcare provider.

BNP is measured in picograms per milliliter (pg/mL) or nanograms per liter (ng/L). Less than 100 pg/mL is considered normal. In general, the more serious your heart failure, the higher your levels of BNP will be. But test results vary by age, sex, and body mass index. Normal values tend to go up with age. They also tend to be higher in women and lower in men. Both men and women who are obese tend to have lower levels.

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward the site may be slightly sore. 

What might affect my test results?

Other things besides heart failure can cause your BNP to rise, including:

  • Kidney failure or being on dialysis

  • Long-term, or chronic, heart failure

  • Nesiritide, a synthetic form of BNP used to treat heart failure

How do I get ready for this test?

You don't need t prepare for this test. Be sure your health care provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don’t need a prescription and any illicit drugs you may use.

Medical Reviewers:

  • Fraser, Marianne, MSN, RN
  • Sather, Rita, RN