What is a BNP Test?

A BNP test is a blood test that checks levels of a chemical compound associated with heart failure. In individuals with healthy hearts, B-type Natriuretic Peptide (BNP) in the blood is usually low. Levels begin to rise when the heart starts to fail, and the higher the levels, the more severe the heart failure. This diagnostic screening test can be ordered in an emergency room as part of a workup on an incoming patient and it may also be recommended by a doctor who is concerned that a patient may be going into heart failure.

B-type Natriuretic Peptide, also known as Brain Natriuretic Peptide, is produced in the ventricles of the heart. The harder the heart has to work, the more BNP the ventricles produce. As heart failure progresses, the heart labors more and more to circulate blood effectively, leading to an increase in this compound. Since it circulates through the blood, a simple blood draw can be used for a BNP test, making it a minimally invasive and also very affordable diagnostic test.

Certain things can cause BNP to rise when a patient is not in heart failure. These include some drug therapies, age, and kidney disease. These factors must be considered when evaluating results to determine how to move forward. One important function of the BNP test is to eliminate some possible diagnoses, such as lung disease, for a patient's symptoms. If the test is positive and a clinician believes that heart failure is a likely diagnosis, a screening, such as echocardiography, can be used to find out what is happening inside the patient.

For the test, a small sample of blood will be needed. Additional vials may be taken to provide a full workup, depending on what the doctor has ordered. The test does not take very long, with results typically available very quickly in a hospital or clinic that has a full service lab. For non-emergencies, a doctor may ask that a patient fast before taking the BNP test for more meaningful results, depending on the case.

It is important to remember that having a high BNP does not automatically mean heart failure. Levels may be elevated for other reasons or the test may not have been performed properly. High levels imply the need for more follow-up and additional diagnostic testing. Patients can discuss the findings of the BNP test with their physicians to determine what would be an appropriate action to take in their case.