BNP — Normal Range & Interpretation

Clinical Context

B-type natriuretic peptide (BNP) is a hormone released by ventricular myocytes in response to increased wall stretch and volume overload. Clinicians use BNP to differentiate cardiac from pulmonary causes of dyspnea and to gauge heart failure severity. Values under 100 pg/mL make heart failure unlikely, while levels above 400 pg/mL strongly support the diagnosis in symptomatic patients.

Elevated BNP reflects heart failure exacerbation, left ventricular hypertrophy, atrial fibrillation, pulmonary embolism, acute coronary syndrome, and chronic kidney disease. Age and female sex also raise baseline values, and obesity falsely lowers results due to clearance by adipose tissue. Sacubitril-valsartan therapy increases BNP because the drug blocks its degradation, so NT-proBNP is the preferred marker in those patients. Depressed values carry little clinical weight outside ruling out heart failure.

What the AANP exam actually tests on BNP: interpretation in the dyspneic patient, distinguishing cardiac from pulmonary etiologies such as COPD exacerbation or pneumonia. Expect questions pairing BNP with physical findings like jugular venous distention, S3 gallop, or bibasilar crackles. Know the diagnostic cutoffs, recognize that obesity lowers results, and understand that BNP trends guide outpatient heart failure management and predict readmission risk after hospital discharge.

Related Labs

• Troponin I — ng/mL
• NT-proBNP — pg/mL
• CK-MB — ng/mL

Sources

• MedlinePlus
• ARUP Consult