A brain natriuretic peptide (BNP) test is a type of blood screening. Doctors use BNP tests to indicate how well the heart is pumping blood throughout the body.
Many healthcare professionals find BNP tests useful in helping diagnose or monitor heart failure.
Read on to learn more about BNP and the levels of BNP that medical experts consider normal. We also outline the BNP test procedure and what the results mean for a person’s heart health.
A BNP test measures levels of BNP in the blood. 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 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.
Other names for BNP or related tests include:
- B-type natriuretic peptide
- N-terminal pro b-type natriuretic peptide
- natriuretic peptides
Doctors often order the BNP test for people they believe 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 heart pressure.
However, any factors that can increase pressure in the heart or stretch its atria chambers, such as blood clots in the lungs — which doctors refer to as pulmonary embolism — can cause elevated BNP levels.
Some signs that an individual may be experiencing heart failure include:
- feeling easily fatigued
- experiencing unexplained swelling in the ankles, feet, legs, and stomach
- weight gain
- shortness of breath
- an inability to lay flat due to shortness of breath
Doctors usually use a BNP test to help detect heart failure. Additionally, they can use the test to help with prognoses, as elevated BNP levels can increase the risk of adverse outcomes, even in those without heart failure. Healthcare professionals may also order a blood screening to investigate what might be contributing to heart failure and to help devise a treatment plan.
Additionally, doctors may 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, which a doctor, nurse, or phlebotomist performs. 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 screening.
A person does not usually need to make any preparations for a BNP test, such as fasting. However, doctors will advise individuals on any specific requirements.
Experts agree there is a healthy range for BNP levels. The cut-off point can vary by laboratory, but commonly, this 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.
However, these values can vary by age, so people should always discuss their results with their doctor.
It is also important to note that some tests can result in falsely low levels, which might indicate normal values of BNP when a person, in fact, does have heart failure.
Several factors can influence an individual’s BNP levels. These
- Age: BNP levels tend to get higher as people get older.
- Gender: Females tend to have slightly higher BNP levels than males
- Certain medications: Drugs, such as angiotensin converting enzyme inhibitors and diuretics, reduce BNP concentrations, while other drugs called beta-blockers can cause levels of BNP to vary.
- Certain medical conditions: The presence of other medical conditions, such as renal failure, liver cirrhosis, hyperthyroidism, or sepsis, 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 their 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 the test shows low or normal levels of BNP, they may rule out the possibility of this condition.
If an individual’s BNP levels are higher than normal, a healthcare professional may recommend additional tests. Examples of these tests include:
- an echocardiogram
- a chest X-ray
- an electrocardiogram
A person can learn how to lower their BNP levels, which they can achieve through various lifestyle changes,
- stopping smoking
- lowering alcohol intake
- relieving stress
- exercising for up to 30 minutes per day
- maintaining a moderate weight
- getting 7–8 hours of sleep each night
- managing diabetes and high blood pressure
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 screenings, such as a chest X-ray and echocardiogram, to check for heart failure.
People should speak with a healthcare professional if they have questions or concerns about their BNP test results.