BNP and NT-proBNP
At a Glance
Why Get Tested?
To diagnose the presence and severity of heart failure
When to Get Tested?
If you have symptoms of heart failure, such as breathlessness and fatigue, or if you are being treated for heart failure
Sample Required?
A blood sample drawn from a vein in your arm
Frequency of testing is at your doctor's discretion or at intervals to monitor for heart failure.
The Test Sample
What is being tested?
These tests measure the concentration of BNP or NT-proBNP in the blood. The heart normally produces low levels of a precursor protein, pro-BNP, which is cleaved to release the active hormone BNP and an inactive fragment, NT-proBNP. The purpose of BNP is to help regulate blood volume and, therefore, the work that the heart must do in pumping blood throughout the body. Both BNP and NT-proBNP are produced mainly in the heart’s left ventricle (the organ’s main pumping chamber). When the left ventricle is stretched from having to work harder, the concentrations of BNP and NT-proBNP in blood can increase markedly. This situation may occur in heart failure as well as other diseases that affect the heart and circulatory system.
How is the sample collected for testing?
Blood is taken by needle from a vein in your arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
The Test
How is it used?
Either BNP or NT-proBNP may be used to help diagnose heart failure and to grade the severity of that heart failure. There are various causes of heart failure. Currently, the condition is diagnosed by the presence of symptoms such as swelling in the legs (oedema), difficulty breathing, shortness of breath, and fatigue, in addition to chest X-rays and an ultrasound test called echocardiography. However, heart failure is still often confused with other conditions. BNP and NT-proBNP levels can help doctors differentiate between heart failure and other problems, such as lung disease. An accurate diagnosis is important because heart failure can be successfully managed with various medical treatments.
When is it requested?
A BNP or NT-proBNP test may be ordered under these circumstances:
- In your doctor's office, if you have symptoms that could be due to heart failure.
- In the emergency room, if you are in crisis and doctors need to quickly determine whether you are suffering from heart failure or some other medical problem.
- To monitor the effects of therapy for heart failure.
What does the test result mean?
Higher-than-normal results suggest that a person is in heart failure, and the level of BNP or NT-proBNP in the blood is related to the severity of heart failure. Higher levels of BNP or NT-proBNP also may be associated with a worse outlook (prognosis) for the patient.
Is there anything else I should know?
BNP is also used as a drug (nesiritide) designed to treat heart failure patients. If you are already on this treatment, your test results may be affected.
BNP and NT-proBNP levels decrease in most patients who have been taking drug therapies for heart failure, such as ACE inhibitors, beta blockers, and diuretics. Levels of both BNP and NT-proBNP tend to increase with age. Levels of NT-proBNP and BNP are increased in persons with kidney disease.
While both BNP and NT-proBNP will rise with left ventricle dysfunction and either can be measured, they are not interchangeable and the results cannot be directly compared.
Common Questions
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Article Sources
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