BNP / NT-proBNP
Brain natriuretic peptide (BNP) and its inactive fragment NT-proBNP are hormones released by heart ventricles when they are stretched by volume overload or pressure overload. They are the primary blood tests for diagnosing and monitoring heart failure. Despite the name, BNP is produced by the heart, not the brain (it was first discovered in brain tissue).
Reference Ranges
Male
0 – 100
pg/mL
Female
0 – 100
pg/mL
Child
Consult pediatrician
Reference ranges may vary by laboratory. Always compare with the range printed on your lab report.
What Low Levels Mean
BNP below 100 pg/mL (or NT-proBNP below 300 pg/mL) effectively rules out heart failure in a patient with shortness of breath. Its negative predictive value is very high — a normal BNP means your shortness of breath is very unlikely to be caused by heart failure.
What High Levels Mean
BNP above 400 pg/mL (or NT-proBNP above 900 pg/mL in adults under 75) strongly suggests heart failure. The higher the level, the more severe the heart failure. BNP is also used to monitor treatment response — decreasing levels indicate the heart is responding to therapy.
Frequently Asked Questions
What is the difference between BNP and NT-proBNP?
Both come from the same precursor protein. BNP is the active hormone (half-life ~20 minutes), while NT-proBNP is the inactive fragment (half-life ~120 minutes). NT-proBNP levels are typically 3–5 times higher than BNP. Different labs use different tests — the reference ranges are different, so don't compare values across tests.
Can BNP be elevated without heart failure?
Yes. Kidney failure raises BNP (impaired clearance), atrial fibrillation, pulmonary embolism, pulmonary hypertension, sepsis, and obesity (lower BNP) all affect levels. Age also matters — BNP reference ranges increase with age. Clinical context is essential for interpretation.
Is BNP used for screening or diagnosis?
Primarily diagnosis — BNP is most useful in emergency settings to determine if shortness of breath is caused by heart failure or lung disease. It is not recommended for population screening. In known heart failure patients, serial BNP measurements help monitor disease severity and treatment response.
This information is for educational purposes only and should not replace professional medical advice. Always consult your doctor for interpretation of your test results.
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