What is the B-type Natriuretic Peptide (BNP) test for?

From the Guidelines

BNP is a test primarily used to diagnose and monitor heart failure, measuring the level of a hormone released by the heart when it's under stress, with elevated levels indicating heart failure and higher levels correlating with more severe disease. The test helps clinicians differentiate between heart failure and other conditions that cause similar symptoms like shortness of breath. BNP testing is particularly valuable in emergency settings to quickly determine if a patient's symptoms are cardiac in origin, as shown in a study published in the journal Circulation 1. It's also useful for monitoring treatment effectiveness in heart failure patients, as levels should decrease with successful therapy.

• Normal BNP levels vary by age and gender, but generally, values below 100 pg/mL suggest heart failure is unlikely, while levels above 400 pg/mL strongly suggest heart failure, as indicated in a study published in the Annals of Internal Medicine 1.
• Some laboratories measure NT-proBNP instead, which is a related marker with similar clinical applications but different reference ranges, as noted in a study published in the European Heart Journal 1.
• The diagnostic accuracy of BNP in heart failure has been evaluated in several studies, including a systematic review and diagnostic meta-analysis published in the BMJ, which found that BNP has high sensitivity and moderate specificity for diagnosing heart failure 1.
• The use of BNP in monitoring therapy has also been studied, with some studies suggesting that it can be useful in guiding treatment decisions, as shown in a study published in Circulation 1. However, the clinical feasibility of a BNP-guided therapeutic strategy is still being debated, and more research is needed to determine its effectiveness.
• In terms of interpretation of BNP values, a position statement from the European Society of Cardiology recommends the following cut-off values: <100 ng/L for heart failure unlikely, 100-500 ng/L for the grey zone, and >500 ng/L for heart failure likely, as indicated in a study published in the European Heart Journal 1.

From the Research

BNP Test Overview

• The B-type natriuretic peptide (BNP) test is used to diagnose and monitor heart failure [(2,3,4,5,6)].
• BNP levels are measured in the blood to determine the presence and severity of heart failure [(2,3,4)].

Diagnostic Uses

• The BNP test is useful in diagnosing heart failure in symptomatic patients without a history of heart failure 4.
• A BNP level of 80 pg/mL is useful in diagnosing heart failure in symptomatic patients 4.
• The test is particularly helpful in ruling out heart failure due to its high negative predictive value [(2,3,6)].

Prognostic Value

• BNP levels are a strong predictor of risk of death and cardiovascular events in patients previously diagnosed with heart failure or cardiac dysfunction 3.
• The test can be used to monitor patients with heart failure and manage their medical therapy accordingly [(3,4)].

Limitations

• BNP levels are not specific for any disease state and can be affected by age, gender, comorbidity, and drug therapy [(2,3,4)].
• The test should not be used in isolation from the clinical context 2.
• BNP values are age and method dependent, even in pediatric populations 5.