A B-type natriuretic peptide (BNP) blood test measures the levels of the BNP hormone in your blood.

BNP and another heart-related hormone called an atrial natriuretic peptide (ANP) work together to keep your veins and arteries widened, or dilated. This allows your blood to easily pass through and prevents clots from forming. BNP and ANP also help your kidneys more easily remove fluid and salt from your body.

When you have congestive heart failure, your heart can’t pump blood properly throughout your body because the walls of your heart chambers, known as the ventricles, become too weak.

This affects pressure and fluid levels in your heart and throughout your body. When this happens, your heart cells produce extra BNP to help maintain the balance of fluids in your body cells and regulate your blood pressure.

A BNP test detects a rise in BNP, which indicates heart failure. Your doctor may recommend this test if you have symptoms of heart failure, such as shortness of breath.

Early diagnosis of heart failure can ensure that you get quick and effective treatment to prevent further complications.

Your doctor may order a BNP blood test if you have symptoms of heart failure, including:

A BNP test can also help rule out heart failure. Other conditions can cause elevated BNP levels, including lung or kidney conditions and obesity.

No special preparation is needed for a BNP test. As it is possible for stress and anxiety to temporarily raise your BNP levels, just do your best to stay calm during the blood draw.

If you faint at the sight of blood or feel weak from fasting, your doctor may recommend that someone come with you in case you’re not able to drive or get yourself home.

A BNP test is done by drawing blood from a vein in your arm using a hypodermic needle. This process is known as venipuncture.

A machine then measures levels of BNP or another heart hormone, called N-terminal-pro BNP (NT-pro-BNP), in the blood sample.

The results from the test are usually ready in 15 to 20 minutes. Results may take up to a week if the blood is sent to a separate lab facility for analysis.

Your results will indicate if your BNP levels are high enough to suspect a diagnosis of heart failure. If you already have a diagnosis of heart failure, the results can help your doctor find out whether heart failure treatments are working.

Generally, BNP levels below 100 picograms per milliliter (pg/mL) are considered normal. But normal BNP levels may vary depending on your age and sex.

Normal BNP range by age and sex

BNP levels increase naturally as you age, and people assigned female at birth typically have slightly higher levels. Underlying conditions can raise your BNP levels, too. Regardless of age or gender, a BNP level of 100 pg/mL or less is considered normal. The higher your level goes above that, the higher your chances are of developing heart failure. Other conditions, like kidney disease, can increase these chances even more.

Your doctor may use BNP tests alongside other diagnostic tests to confirm if you have heart failure, or if other conditions are responsible for the increase in your BNP levels.

The chart below shows the normal range, as well as the cutoff levels for a heart failure diagnosis at different ages. These figures use data from a specific type of BNP test called the N-terminal (NT)-pro hormone BNP (NT-proBNP).

Age RangeBNP LevelWhat It Means
All agesUnder 100 pg/mLNormal
Ages 50 and older450 pg/mL and upAcute heart failure
Ages 50 to 75900 pg/mL and upAcute heart failure
Ages 75 and older1,800 pg/mL and upAcute heart failure

What do high or low BNP levels mean?

In most cases, a high BNP is the greater cause for concern. As your BNP level increases above 100 pg/mL, your chances of developing heart failure increase. These changes already increase with age, so early increases in your BNP level could be cause for alarm.

Generally, anything over 100 pg/mL can indicate some level of heart failure. Heart failure is graded in terms of your ejection fraction, or the amount of blood your heart pumps out with every beat. The ejection fraction is a rough estimate of how well your heart is functioning. For example, an EF of 50% to 70% is normal, and this means that your heart is functioning at about 50% to 70% of its potential. It’s possible to have heart failure with a normal EF, but in many cases, your heart’s overall function will decrease as your heart failure worsens.

In acute heart failure, your heart function is severely limited — to the point where even regular daily activities like cooking and bathing can be a strain. Depending on your age, a BNP result of 400 pg/mL to 1,800 pg/mL signals acute heart failure.

While a high BNP level is more well-known for being worrisome, some studies suggest that a low BNP can also be a sign of heart trouble. In one study, a small portion of people hospitalized for conditions like heart failure, abnormal heart structure or function, and abnormal hemodynamics (heart rate, blood pressure, and similar readings) had lower than normal BNP levels. Some were so low, in fact, that they couldn’t even be detected on lab tests.

This test has a 98 percent success rate in ruling out heart failure as a cause of increased BNP levels.

Exercise may cause BNP levels to rise temporarily. Stress can raise your levels of the hormone cortisol, which can also temporarily increase BNP levels.

To confirm a heart failure diagnosis, your doctor may also recommend the following tests:

There are no serious risks to having a BNP test performed. Like most tests performed by venipuncture, drawing blood from your vein could cause symptoms like:

  • soreness
  • bruising
  • bleeding
  • lightheadedness

These symptoms are usually short-lived if they develop at all. If you’re concerned about getting lightheaded, you may want to make sure someone drives you home afterward.

If you have symptoms of heart problems like shortness of breath or chest pain, not having a BNP test performed may pose greater risks than the test itself. Early detection of heart failure can help you get treatment sooner and may improve your overall prognosis.

Improving your heart health can help reduce the effects of heart failure and other heart conditions. Consider these heart-healthy steps:

  • If you smoke, talk with your doctor about setting up a quit plan.
  • Stop consuming alcohol altogether, or drink fewer alcoholic beverages.
  • If you are overweight or have obesity, work with your doctor to create a sustainable weight management plan.
  • Manage stress through practices such as yoga or meditation.
  • Exercise more often than not. Aim for at least 150 minutes of exercise a week.
  • Get 7 to 9 hours of sleep a night.

Depending on the cause of your heart failure and other conditions, your doctor may recommend the following:

If high BNP levels indicate heart failure, your doctor will tell you the steps to take to prevent complications of this condition.

See your doctor regularly to monitor your BNP levels if needed, and follow any instructions to maintain your best heart health.

Are BNP tests covered by Medicare?

In general, most blood tests ordered by your doctor as medically necessary to diagnose or treat a condition are usually covered by Medicare. In the case of BNP testing, this testing is covered, but with some restrictions. The test may not be covered as a stand-alone test, or as a tool for monitoring congestive heart failure. Additionally, Medicare will usually only cover up to four BNP tests each year.

BNP is a blood test that is used to help diagnose conditions like heart failure. This test is commonly done in the emergency department if you show up with symptoms like shortness of breath. High BNP levels are usually associated with an increased risk of developing heart failure, but low BNP levels can also signal some heart problems.

If your doctor orders a BNP test for you, they will interpret your results based on your individual age, gender, and other health conditions.