Brain natriuretic peptide test
Brain natriuretic peptide (BNP) test is a blood test that measures levels of a protein called BNP that is made by your heart and blood vessels. BNP levels are higher than normal when you have heart failure.
If you cough a lot, often feel weak, have lost your appetite, and need to urinate a lot at night, you might have symptoms of heart failure. Heart failure is a long-term condition that usually comes on slowly. However, it can develop suddenly, for instance, after a heart attack. You have heart failure when your heart does not pump blood out of your heart very well, or when your heart muscles are stiff and do not easily fill up with blood. When you have heart failure, your heart cannot pump enough oxygen-rich blood to the rest of your body, especially when you exercise or move around a lot. As the heart loses the ability to pump blood, blood backs up in other parts of your body, including your lungs, liver, gastrointestinal tract, and your arms and legs. The most common cause of heart failure is coronary artery disease, the narrowing of the blood vessels that supply blood and oxygen to your heart. So, how do you know if you have heart failure? Get to your doctor. You may have trouble breathing, an irregular heartbeat, swollen legs, neck veins that stick out, and sounds from fluid built up in your lungs. Your doctor will check for these and other signs of heart failure. A test called an echocardiogram is often the best test to diagnose your heart failure. Your doctor can also use this test to find out why you have heart failure, and then monitor your condition going forward every three to six months. Your doctor will talk to you about knowing your body and symptoms that mean your heart failure is getting worse. You will need to learn to watch for changes in your heart rate, pulse, blood pressure, and weight. You will also need to limit salt in your diet, stop drinking alcohol, quit smoking if you need to, exercise, lose weight if you need to, and get enough rest. Your doctor will probably ask you to take medicines to treat your heart failure. These medicines can treat your symptoms, prevent your heart failure from getting worse, and help you live longer. If you have heart failure, taking your medicines, changing your lifestyle, and treating the condition that caused heart failure can go a long way toward improving your health. But heart failure is a chronic, or long-term, illness, which means it may get worse over time. Make sure you call your doctor if you start coughing more, have sudden weight gain or swelling, or feel week. Have someone take you to the emergency room right away if you have trouble with fainting, a fast and irregular heartbeat, or feel severe crushing chest pain.
How the Test is Performed
A blood sample is needed. The blood is taken from a vein (venipuncture).
This test is most often done in the emergency room or hospital. Results take up to 15 minutes. In some hospitals, a finger prick test with rapid results is available.
How the Test will Feel
When the needle is inserted to draw blood, you may feel a little pain. Most people feel only a prick or a stinging sensation. Afterward there may be some throbbing or bruising.
Why the Test is Performed
You may need this test if you have signs of heart failure. Symptoms include shortness of breath and swelling of your legs or abdomen. The test helps make sure the problems are due to your heart and not your lungs, kidneys, or liver.
It is unclear if repeated BNP tests are helpful in guiding treatment in those already diagnosed with heart failure.
Normal Results
In general, results of less than 100 picograms/milliliter (pg/mL) suggest a person does not have heart failure.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your health care provider about the meaning of your specific test results.
What Abnormal Results Mean
BNP levels go up when the heart cannot pump the way it should.
A result greater than 100 pg/mL is abnormal. The higher the number, the more likely heart failure is present and the more severe it is.
Sometimes other conditions can cause high BNP levels. These include:
- Kidney failure
- Pulmonary embolism
- Pulmonary hypertension
- Severe infection (sepsis)
- Lung problems
Risks
Risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Considerations
A related test, called the N-terminal pro-BNP test, is done in the same way. It provides similar information, but the normal range is different.
References
Bock JL. Cardiac injury, atherosclerosis, and thrombotic disease. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 19.
Felker GM, Teerlink JR. Diagnosis and management of acute heart failure. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 49.
Heidenreich PA, Bozkurt B, Aguilar D, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2022;145(18):e895-e1032. PMID: 35363499
Version Info
Last reviewed on: 10/5/2022
Reviewed by: Thomas S. Metkus, MD, Assistant Professor of Medicine and Surgery, Johns Hopkins University School of Medicine, Baltimore, MD. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
