BNP / NT-proBNP (Heart Failure Marker)
Also known as: B-type natriuretic peptide, Brain natriuretic peptide, NT-pro-BNP
BNP and NT-proBNP are hormones released by stretched heart muscle — they are the primary blood tests for diagnosing heart failure and monitoring treatment response.
Venous blood (EDTA for BNP; serum for NT-proBNP)
1–4 hours
Not required
Cardiac Markers
Reference Ranges
| Measurement | Reference Range | Unit |
|---|---|---|
| BNP (heart failure unlikely) | ≤ 100 | pg/mL |
| BNP (heart failure likely) | ≥ 400 | pg/mL |
| NT-proBNP (< 50 years, likely) | ≥ 450 | pg/mL |
| NT-proBNP (50–75 years, likely) | ≥ 900 | pg/mL |
| NT-proBNP (> 75 years, likely) | ≥ 1800 | pg/mL |
Reference ranges are typical adult values. Your laboratory may use slightly different intervals — always use your lab's reported reference.
What This Test Measures
When the ventricular myocardium is stretched (by volume overload or high pressures), it releases pro-BNP, which is cleaved into BNP (biologically active) and NT-proBNP (inactive fragment). Both are proportional to the degree of cardiac stress. BNP has a 20-minute half-life; NT-proBNP has a 1–2 hour half-life — NT-proBNP is more stable and affected more strongly by kidney function.
When Is This Test Ordered?
- Distinguishing cardiac from pulmonary causes of dyspnoea in the emergency department
- Diagnosing heart failure in ambulatory patients
- Monitoring heart failure treatment response and guiding therapy intensification
- Prognostication in acute coronary syndrome
When Results Are High
Markedly elevated BNP (above 400 pg/mL) or NT-proBNP makes heart failure highly likely. Each doubling of NT-proBNP correlates with a roughly 35% increase in mortality risk. Values between 100–400 pg/mL (BNP) or age-adjusted intermediate ranges (NT-proBNP) require clinical correlation.
When Results Are Low
BNP below 100 pg/mL has a very high negative predictive value for heart failure — dyspnoea is very unlikely to be cardiac. This makes it extremely useful in the emergency setting for ruling out acute heart failure without an echocardiogram.
Factors That Can Affect Your Result
- Kidney disease raises both markers — use NT-proBNP age-adjusted cut-offs for eGFR below 60
- Obesity lowers BNP despite equivalent cardiac stress — obese patients may have more cardiac disease at lower BNP levels
- Atrial fibrillation raises BNP/NT-proBNP even without LV dysfunction
- BNP is less stable at room temperature — process within 4 hours or use NT-proBNP
Tracking This Test Over Time
In treated heart failure, a 30% fall in NT-proBNP over 2–4 weeks indicates effective decongestion. A rising NT-proBNP despite treatment signals inadequate response and need for intensification. Track your NT-proBNP trend with your cardiologist to optimise therapy before symptoms worsen.
Track your BNP / NT-proBNP in LoomsRelated Tests
Troponin
Troponin is the gold-standard biomarker for diagnosing heart muscle damage. High-sensitivity troponin assays can detect injury within 1–3 hours of a heart attack, enabling faster rule-in and rule-out of acute myocardial infarction.
Creatinine / eGFR
Creatinine is a waste product filtered by the kidneys; eGFR (estimated glomerular filtration rate) converts it into a percentage of normal kidney function. Together they are the primary tools for detecting and staging chronic kidney disease.
Medical disclaimer
This page is for educational purposes only and does not constitute medical advice. Reference ranges vary between laboratories, and results must be interpreted in the context of your symptoms, history, and other tests. Always discuss your results with your healthcare provider. Content reviewed by the Looms medical team, 2026-06-01.