In evaluating dyspnea, when is BNP measurement most useful?

• A. BNP is elevated in all respiratory infections.
• B. BNP can support the assessment of heart failure when dyspnea is present.
• C. BNP alone diagnoses heart failure with certainty.
• D. BNP is not useful in evaluating dyspnea.

Answer: (B)

BNP measurement is most useful for distinguishing whether heart failure is contributing to a patient’s dyspnea. BNP is released by the ventricles in response to stretch and volume overload, so elevated levels support cardiac involvement as a cause of shortness of breath and help separate it from noncardiac issues like COPD, pneumonia, or other lung conditions. It’s a helpful adjunct when the clinical picture is unclear and you’re deciding on further testing or treatment, such as diuresis or referral for echocardiography.

Keep in mind it’s a supportive test, not a standalone diagnosis. Levels can be influenced by factors like obesity, older age, and renal dysfunction, and a normal BNP doesn’t completely exclude heart failure in every case. Nonetheless, in the context of dyspnea, BNP provides meaningful insight into whether heart failure is likely contributing to the symptoms.