BNP and NT-proBNP
- Also Known As:
- Brain Natriuretic Peptide Test
- N-Terminal Pro B-Type Natriuretic Peptide Test
- Natriuretic Peptide Test
Test Quick Guide
Natriuretic peptides are proteins produced by the heart and blood vessels. Two of these proteins—brain natriuretic peptide (BNP) and N-terminal pro b-type natriuretic peptide (NT-proBNP)—may be measured in the blood to help diagnose congestive heart failure and several other health conditions.
BNP and NT-proBNP tests are often performed in a hospital or emergency room. They may be conducted with a blood sample from a vein in your arm or with a rapid fingerstick test.
About the Test
Purpose of the test
The main purpose of BNP or NT-proBNP testing is to see if the blood levels of these proteins are within the expected range for a healthy person. These tests are most commonly used for diagnosis but may be involved in other health assessments.
Diagnosis is the process of finding the underlying cause of symptoms. BNP and NT-proBNP tests are often used to determine if a patient has heart failure. Heart failure is a condition in which the heart is not pumping blood properly to the rest of the body, but it does not mean that the heart has stopped.
People with congestive heart failure may experience various symptoms, including swelling and shortness of breath. However, these symptoms can be caused by many other conditions besides heart failure. BNP and NT-proBNP testing can be used to help find out if heart failure or some other condition is the cause of a patient’s symptoms.
BNP and NT-proBNP testing may also be used to evaluate people who have already been diagnosed with congestive heart failure. In these patients, testing may be ordered to assess the severity of the disease and its likely course or prognosis. Less often, BNP or NT-proBNP tests may be considered when determining what type of treatment to prescribe or when monitoring a patient’s health over time.
What does the test measure?
These tests measure blood levels of BNP or NT-proBNP, which are proteins that are made by the heart and blood vessels. These hormones are secreted into the bloodstream in response to excess fluid accumulating in the blood vessels. The active hormone, BNP, encourages the removal of water and salt from the blood.
When should I get a BNP or NT-proBNP test?
Your doctor may order a BNP or NT-proBNP test if you have symptoms of heart failure. If you have already been diagnosed with heart failure, your doctor might order a test to get more information about your condition.
The main symptoms of heart failure are:
- Shortness of breath or difficulty breathing
- Swelling of your legs, ankles, or abdomen
Shortness of breath is extremely common among people who have congestive heart failure, but this symptom can also occur in other conditions such as lung, kidney, and liver disease. For this reason, your doctor is likely to order a BNP or NT-proBNP test if you have unexplained shortness of breath.
Finding a BNP or NT-proBNP Test
How to get tested
Your doctor will decide if BNP or NT-proBNP testing is appropriate in your situation. The test is usually done in a hospital and frequently is performed in the emergency room. The test can also be done in a doctor’s office or outpatient laboratory or clinic.
Can I take the test at home?
BNP and NT-proBNP testing is not currently available for at-home sample collection or testing.
How much does the test cost?
The cost of a BNP or NT-proBNP test varies depending on where the test is conducted, whether you have health insurance, and, if you do, what your insurance covers. The final cost of the test may reflect several services, including charges for:
- The health care provider who draws your blood
- Expenses from the laboratory that processes your blood sample
- Consultations with the physicians who prescribe the test, interpret the results, and review their findings with you
Most health insurance policies cover the cost of tests prescribed by your physician, but you may be responsible for a deductible or copayment. If this is a concern for you, your health insurance provider can tell you what you are likely to owe.
Contacting your insurance provider ahead of time may be an option if the test has been scheduled to help your doctor monitor your condition. However, BNP and NT-proBNP tests are often done in emergency settings, so there may not always be time to contact your insurance provider about coverage prior to the test.
Taking a BNP or NT-proBNP test
A blood sample is needed for a BNP or NT-proBNP test. This blood sample can be drawn from a vein in your arm. In emergency settings, a blood sample for rapid testing may be obtained by pricking your finger with a small needle.
Before the test
No preparation is needed for a BNP or NT-proBNP test.
During the test
The BNP or NT-proBNP test may be performed using a blood sample taken from a vein in your arm during a process called venipuncture. In this procedure, a health professional will cleanse the puncture area with an antiseptic wipe and then insert a small needle into your vein. The needle is used to collect the blood in a test tube or vial.
You may feel a brief stinging sensation when the needle is inserted or withdrawn. The process of collecting a sample usually takes no more than 5 minutes.
Some hospitals use a fingerstick test that provides more rapid results than the venipuncture method. To do a fingerstick test, a health professional pricks your finger with a very small needle to collect a few drops of blood. The blood is placed onto a strip of test paper and inserted into an electronic device that provides results within a few minutes.
After the test
Once your blood is drawn, a bandage will be applied to the puncture site. Unwanted effects following a blood draw are rare. The risks are very low, but some of these may occur:
- Excessive bleeding
- Fainting or feeling lightheaded
- Slight bruising
You should tell your doctor if you have any lasting or worsening effects after your blood draw.
BNP or NT-proBNP Test Results
Receiving test results
The results from a BNP or NT-proBNP test can be ready in as little as 15 to 20 minutes for rapid fingerstick tests. The results after a blood draw may take up to a few days to become available.
You may receive your results through an electronic messaging system or online health portal. If you are hospitalized, you are likely to receive them in person from a doctor.
Interpreting test results
The report you receive from the laboratory or from your doctor will show your measured level of BNP or NT-proBNP. This is often measured in picograms per milliliter (pg/mL) but may be listed by some labs in nanograms per liter (ng/L) or picomoles per liter (pmol/L).
Along with your BNP or NT-proBNP level, the test results will include the reference range, which represents the expected levels in a healthy adult. The reference range may vary slightly among laboratories. Check your test report for the reference range and the units used by the lab.
In general, people with congestive heart failure frequently have BNP levels that are greater than 100 pg/mL. Often, congestive heart failure causes BNP levels to be much higher. However, having a BNP level below 100 pg/mL does not rule out heart failure, and a BNP level above 100 pg/mL alone is not enough to diagnose heart failure.
In addition, other health conditions can cause BNP or NT-proBNP levels to be elevated. Examples of these conditions include:
- Kidney failure
- Heart disease
- Cardiomyopathy, which is a disease affecting the heart muscle
- Pulmonary hypertension, which is high blood pressure in the arteries that bring blood to the lungs
- Sepsis, which is an extreme response to infection
Other factors like age, sex, body weight, and genetics can influence your BNP and NT-proBNP levels. For that reason, your doctor will consider not just the laboratory reference range but also your age when interpreting your test result. They will also review your symptoms, medical history, and other test results.
It is essential to talk with your health care provider in order to best understand your BNP or NT-proBNP test result.
Are test results accurate?
Many variables affect the accuracy and interpretation of the BNP and NT-proBNP tests, which is why it is so important to discuss your results with your physician.
For example, some factors that may affect test accuracy include:
- Type of test: There can be some variation in results from rapid tests and tests analyzed by a laboratory. Reference ranges may also differ by laboratory.
- Individual factors: The expected BNP and NT-proBNP level in healthy people varies by age. A doctor will also take into account your sex, genetics, and body mass index (BMI) when interpreting your results.
- Other health conditions: More than one type of health problem can cause BNP or NT-proBNP levels to be elevated, which means that this test alone may not be able to diagnose congestive heart failure or another condition.
If you have any questions about the accuracy of your test results, talk with your health care provider to learn more about the type of test you had and its significance for your health.
Do I need follow-up tests?
If your BNP or NT-proBNP results suggest that you have congestive heart failure, your physician may order more tests to clarify the extent of your illness and guide treatment decisions. Follow-up testing might include additional BNP or NT-proBNP tests as well as other blood tests, imaging tests, or a cardiac stress test.
If you have symptoms like shortness of breath or swelling but have a normal BNP or NT-proBNP level, the doctor may recommend additional tests to help identify the cause of your symptoms.
Questions for your doctor about test results
The best way to understand your test results and your condition is to ask your doctor questions. For example, these questions may be helpful to discuss:
- What did you learn from my BNP or NT-proBNP test?
- How often do I need to get this test?
- What can I do to improve my health and test results?
- What signs or symptoms might alert me that my condition is worsening?
- Do I need any other tests?
BNP or NT-proBNP tests vs. ANP tests
Atrial natriuretic peptide (ANP) is a protein similar to BNP and NT-proBNP. ANP is released in much lower concentrations than BNP during heart failure. For this reason, although ANP is tested occasionally, BNP or NT-proBNP testing provides more useful diagnostic information in most cases.
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