NT-proBNP (N-terminal pro-B-type natriuretic peptide) is a blood test used to help diagnose or rule out heart failure. When the heart is under strain, it releases BNP and NT-proBNP into the blood. Higher levels suggest the heart is working harder than normal. It is the preferred test in Australian and international guidelines for initial assessment of suspected heart failure. A normal result makes heart failure very unlikely. An elevated result does not confirm heart failure — it means further investigation (usually an echocardiogram) is needed.

What is the difference between BNP and NT-proBNP?

Both are released by the heart under strain, but they are different molecules with different reference ranges. NT-proBNP has a longer half-life and higher absolute values — a normal NT-proBNP is up to 125 pg/mL in under 75s, while a normal BNP is up to 100 pg/mL. The results are not interchangeable. Most Australian labs report NT-proBNP. Check which test your lab used before interpreting the result.

What NT-proBNP level indicates heart failure?

NT-proBNP levels for ruling out heart failure are age-dependent. For acute presentation: heart failure is unlikely below 300 pg/mL at any age. For non-acute presentation: heart failure is unlikely below 125 pg/mL for age under 75, or below 450 pg/mL for age 75 and over. Levels above these thresholds do not confirm heart failure — they indicate further investigation (echocardiogram) is warranted. Levels can also be elevated by kidney disease, atrial fibrillation, pulmonary embolism, sepsis, and obesity can cause falsely low results.

NT-proBNP / BNP Interpreter

Enter the result and patient age. See if heart failure is likely, possible, or unlikely.

📋 Source: ESC 2021 Guidelines for the Diagnosis and Treatment of Heart Failure (McDonagh et al., European Heart Journal 2021). NICE NG106 — Chronic Heart Failure. National Heart Foundation of Australia — Guidelines for the Prevention, Detection and Management of Heart Failure. NT-proBNP age-stratified acute thresholds per Januzzi et al., Eur J Heart Fail 2006.
Your doctor or healthcare provider knows your history and circumstances — always follow their personalised advice over general information.

🌏 Works for all countries

Clinical tool — for healthcare professionals. This interpreter provides general guidance only. NT-proBNP and BNP must be interpreted in clinical context. Elevated levels do not confirm heart failure — further investigation is needed. Your clinical judgement applies.

Test type

Result (pg/mL)

Patient age

Presentation

NT-proBNP reference thresholds

Setting	Heart failure unlikely	Grey zone	Heart failure likely
Acute (any age)	<300	300–450 / 900 / 1,800*	>450 (<50y) / >900 (50-75y) / >1,800 (75+)
Non-acute (GP)	<125	125–450	>450 (or >125 if <75y)

*Acute age-stratified thresholds per ESC 2021 guidelines. All values in pg/mL (= ng/L). Some labs report in pmol/L — divide by 0.118 to convert to pg/mL.

BNP reference thresholds

Setting	Heart failure unlikely	Heart failure likely
Acute	<100	>400
Non-acute (GP)	<35	>100

What can affect the result?

⬆️ Falsely elevated

Atrial fibrillation

Chronic kidney disease (eGFR <60)

Pulmonary embolism

Pulmonary hypertension

Sepsis / critical illness

Advancing age

Anaemia

⬇️ Falsely low

Obesity (BMI >35)

Flash pulmonary oedema (tested too early)

Constrictive pericarditis

End-stage cardiomyopathy (burned out)

Stable treated heart failure (on optimal therapy)

1. Echocardiogram — the next step for any elevated NT-proBNP. This confirms or excludes structural heart disease and measures ejection fraction (EF). Refer for transthoracic echo.

2. ECG — if not already done. A completely normal ECG makes heart failure very unlikely (negative predictive value >98%).

3. Bloods — FBC, UEC (renal function), LFTs, TFTs, iron studies, HbA1c, lipids. Looking for causes and comorbidities.

4. Chest X-ray — if acute symptoms. Look for cardiomegaly, pulmonary congestion, pleural effusions.

5. Consider referral — to cardiology if echo confirms reduced EF, or if diagnostic uncertainty. Urgent referral if severe symptoms (NYHA III-IV).

Most Australian pathology labs report NT-proBNP. It has a longer half-life and is less affected by acute haemodynamic changes. Either is acceptable for ruling out heart failure — but check which one your lab offers and use the correct reference range. The two tests are not interchangeable — their numbers are very different.