A brain natriuretic peptide (BNP) test is a type of blood test. Doctors use the BNP family of tests as an indicator of how well the heart is pumping blood around the body. Many doctors find it useful in helping to diagnose or monitor heart failure.
Read on to find out more about BNP and the levels of BNP that medical experts consider normal. We also outline the BNP test procedure and what the results can tell a person about their heart health.
A BNP test measures levels of BNP in the blood.
Other names for BNP or related tests include:
- B-type natriuretic peptide
- N-terminal pro b-type natriuretic peptide
- natriuretic peptides
BNP is a hormone that the left ventricle of the heart produces to help regulate blood volume.
The left ventricle is the part of the heart that is chiefly responsible for pumping oxygenated blood around the body. If a person's heart has difficulty pumping blood, it releases more BNP than usual. For this reason, doctors often use the BNP test as an indicator of how efficiently the heart is pumping.
Doctors often order the BNP test for people they suspect may experiencing heart failure. Heart failure is where a person's heart does not pump blood efficiently enough to support their body's needs or when the heart does not relax normally, leading to elevated pressure in the heart.
However, any factors that can increase the pressure in the heart or stretch the atria chambers of the heart, such as blood clots in the lungs (pulmonary embolism), can cause elevated BNP levels.
Some signs that a person may be experiencing heart failure include:
- feeling easily fatigued
- experiencing shortness of breath
- experiencing unexplained swelling in the ankles, feet, legs, and stomach
- weight gain
- shortness of breath
Doctors usually use one of the BNP tests in combination with other blood tests that can help detect heart failure. Doctors can also use the test to help with prognoses, as elevated levels of BNP can increase the risk of adverse outcomes, even in people without heart failure.
Doctors may also use the BNP test to assess how well a person's heart failure treatments are working.
The BNP test follows a standard blood test procedure.
A doctor, nurse, or phlebotomist will perform the blood test. A phlebotomist is a person trained in drawing blood.
The medical professional will:
- apply a tight band, or tourniquet, around the arm to make the veins more prominent and easier to identify
- clean the skin over and around the vein
- insert a small, hollow needle into the vein and collect the blood in a tube
- remove the tourniquet and apply gauze or bandage to the area to stop any bleeding
Most people can resume their normal activities immediately after the blood test.
A person does not usually need to make any preparations for the test, such as fasting. However, a doctor will advise individuals on any specific requirements.
Experts agree that there is a healthy range for BNP levels. The cut-off point can vary by laboratory, but commonly, the healthy range is less than 100 picograms of BNP per milliliter (pg/ml) of blood. This means that a result of more than 100 pg/ml indicates the possibility of heart failure.
Values can vary by age, however, so people should always discuss their results with their doctor.
It is important to note that some tests can result in false negatives, which might indicate normal values of BNP when a person does have heart failure.
According to the European Heart Journal, several factors can influence a person's BNP levels. These include:
- Age: A person's BNP levels tend to get higher as they get older.
- Gender: Women tend to have slightly higher BNP levels than men, according to an article in the
- Certain medications: Drugs such as ACE inhibitors and diuretics reduce BNP concentrations, while drugs called beta-blockers can cause levels of BNP to vary.
- Certain medical conditions: The presence of other medical conditions, such as renal failure, can affect BNP levels.
Ultimately, many factors can affect BNP levels. A doctor will interpret a person's results alongside those of other tests. They will also consider the person's overall health and whether or not they have any symptoms.
Doctors typically use the BNP test as an indicator of whether a person is experiencing heart failure. If a test shows low or normal levels of BNP, the doctor may rule out the possibility of heart failure.
If a person's BNP levels are higher than normal, the doctor may recommend additional tests.
Examples of these tests include:
- an echocardiogram
- a chest X-ray
- an electrocardiogram (EKG)
The BNP is one of a family of blood tests that measure levels of brain natriuretic peptide in the blood. It is one of several tests that doctors may use to help diagnose heart failure.
If a person's BNP levels are higher than normal, a doctor may order additional blood tests to check for heart failure.
A person should talk to their doctor if they have questions or concerns about their BNP test results.