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

BNP and another heart hormone called 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 make sure 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:

  • trouble breathing (dyspnea)
  • feeling exhausted or weak for no apparent reason
  • rapid weight gain without a change in diet or activity
  • inability to concentrate or remain alert
  • abnormally high or irregular heart rate
  • coughing a lot, and producing white or pink phlegm
  • nausea or having no appetite

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.

You may want to have someone take you home. 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 to be ready if the blood is sent to a separate laboratory 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 helping treat it.

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 higher levels. Underlying conditions can raise your levels too.

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.

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:

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

  • If you smoke, talk with your doctor about setting up a quit plan.
  • Stop consuming alcohol altogether, or drink fewer alcoholic beverages.
  • If you have overweight or 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 let you know what steps you need to take to prevent complications of this condition.

See your doctor regularly to monitor your BNP levels if needed. Follow any instructions your doctor gives you to maintain your best heart health.