When heart failure develops or worsens, the ventricles or lower chambers of the heart produce a substance that breaks down to form two proteins: B-type natriuretic peptide (BNP) and N-terminal-pro-BNP (NT-pro-BNP). Both substances are secreted in response to changes in pressure that occur with heart failure. BNP and NT-pro-BNP levels in the blood increase when heart failure symptoms worsen, and decrease when the heart failure condition is stable. The test is able to detect heart failure over 80% of the time.
BNP and NT-pro-BNP levels in a person with heart failure -- even someone whose condition is stable -- are higher than in a person with normal heart function.
The symptoms of heart failure can be related to the pooling of fluid in the body or can be secondary to decreased blood flow to the body. Some people with heart failure don't experience symptoms, but here are some of the more common signs:
Shortness of breath with exercise or difficulty breathing at rest or when lying down
Swollen legs, ankles, or abdomen
Dry, hacking cough, or wheezing
Other symptoms may include:
Fatigue, palpitations, or pain during normal activities
BNP levels help to determine if you have heart failure, rather than another condition that may cause similar symptoms. In addition, BNP testing helps your doctor determine if your heart failure has worsened, evaluate what other treatments are needed, if you need to be hospitalized, and to determine a prognosis (how well you will do in the future). Depending on which tests are available at your medical center, the BNP and/or NT-pro-BNP test may be performed. Both tests have been shown to be beneficial.
What Happens During a BNP Blood Test?
During a BNP blood test, a small amount of blood is taken and placed in a machine that detects the level of BNP and NT-pro-BNP. The test takes about 15 minutes. In some places, the blood sample needs to be sent off site to a lab to be tested.
What Do the Results of the BNP Blood Test Mean?
The level of BNP tends to increase with the level of disease severity but can also increase with age. Testing BNP levels is one of the most sensitive ways to assess how well you're doing on heart failure treatment.
In recent studies, patients who had an elevated level of either BNP or NT-pro-BNP had a higher risk of death and illness from heart failure.
Ask your health care provider to explain the results of your BNP tests.