What are natriuretic peptide tests (BNP, NT-proBNP)?
Natriuretic peptides are substances made by the heart. Two main types of these substances are brain natriuretic peptide (BNP) and N-terminal pro-b-type natriuretic peptide (NT-proBNP). Normally, only small levels of BNP and NT-proBNP are found in the bloodstream. High levels can mean your heart isn’t pumping as much blood as your body needs. When this happens, it’s known as heart failure, sometimes called congestive heart failure.
Natriuretic peptide tests measure the levels of BNP or NT-proBNP in your blood. Your health care provider may order a BNP test or an NT-proBNP test, but not both. They are both useful in diagnosing heart failure, but rely on different types of measurements. The choice will depend on the equipment available in your provider’s recommended laboratory.
Other names: brain natriuretic peptide, NT-proB-type natriuretic peptide test, B-type natriuretic peptide
What are they used for?
A BNP test or an NT-proBNP test is most often used to diagnose or rule out heart failure. If you’ve already been diagnosed with heart failure, the test may be used to:
- Find out the severity of the condition
- Plan treatment
- Find out if treatment is working
The test may also be used to find out whether or not your symptoms are due to heart failure.
Why do I need a natriuretic peptide test?
You may need a BNP test or an NT-proBNP test if you have symptoms of heart failure. These include:
- Difficulty breathing
- Coughing or wheezing
- Swelling in abdomen, legs, and/or feet
- Loss of appetite or nausea
If you are being treated for heart failure, your health care provider may order one of these tests to see how well your treatment is working.
What happens during a natriuretic peptide test?
For a BNP test or an NT-proBNP test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for the test?
You don’t need any special preparations for a BNP test or an NT-proBNP test.
Are there any risks to the test?
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
What do the results mean?
If your BNP or NT-proBNP levels were higher than normal, it probably means you have heart failure. Usually, the higher the level, the more serious your condition is.
If your BNP or NT-proBNP results were normal, it probably means your symptoms are not being caused by heart failure. Your provider may order more tests to help make a diagnosis.
If you have questions about your results, talk to your health care provider.
Is there anything else I need to know about a natriuretic peptide test?
Your health care provider may order one or more of the following tests in addition to or after you’ve had a BNP or NT-proBNP test:
- Electrocardiogram, which looks at the heart’s electrical activity
- stress test, which shows how well your heart handles physical activity
- Chest x-ray to see if your heart is larger than normal or if you have fluid in your lungs
You may also get one or more of the following blood tests:
- ANP test. ANP stands for atrial natriuretic peptide. ANP is similar to BNP but it is made in a different part of the heart.
- Metabolic panel to check for kidney disease, which has similar symptoms to heart failure
- Complete blood count to check for anaemia or other blood disorders