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 (
edema), 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.
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.
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.