---
title: Natriuretic peptide test (BNP and NT-proBNP)
description: What BNP and NT-proBNP are, why they are measured when heart failure is suspected, and how doctors use the result.
type: diagnostic
aliases:
  - BNP
  - NT-proBNP
  - brain natriuretic peptide
  - B-type natriuretic peptide
sources:
  - tier: guideline
    org: nice
    title: 'Chronic heart failure in adults: diagnosis and management (NG106)'
    year: 2025
    url: https://www.nice.org.uk/guidance/ng106
  - tier: review
    title: Heart Failure Association of the European Society of Cardiology practical guidance on the use of natriuretic peptide concentrations
    year: 2019
    doi: 10.1002/ejhf.1494
  - tier: reference
    org: statpearls
    title: Natriuretic Peptide B Type Test
    year: 2025
    url: https://www.ncbi.nlm.nih.gov/books/NBK556136/
sources_checked: 2026-10-11
review: null
---

BNP (B-type natriuretic peptide, previously called brain natriuretic peptide) and NT-proBNP are substances the heart releases when its walls are stretched; their levels are measured with an ordinary blood test.<Cite n={3} /> The higher the level, the more likely it is that breathlessness is caused by [heart failure](../../disease/heart-failure/).<Cite n={2} /> The test does not make a diagnosis on its own: a doctor always looks at it together with other information.<Cite n={2} />

<Diagram name="natriuretic-peptides">
  <p slot="scheme">The heart makes proBNP, which splits into two parts: the active hormone BNP and the inactive fragment NT-proBNP.<Cite n={3} /></p>
</Diagram>

## What it shows

<Patient>

The heart makes a precursor protein, proBNP, which splits into two parts: the active hormone BNP and the inactive fragment NT-proBNP.<Cite n={3} /> BNP comes mainly from cells in the heart's ventricles, especially when the ventricles are stretched.<Cite n={3} /> BNP helps the body get rid of water and salt and widens blood vessels, which lowers blood pressure.<Cite n={3} />

So the level of these peptides reflects the strain on the heart: high pressure and a large volume of blood in its chambers.<Cite n={2} />

</Patient>

<Student>

ProBNP is cleaved by corin into equimolar amounts of biologically active BNP and inactive NT-proBNP.<Cite n={3} /> End-diastolic wall stress, intracardiac filling pressures and intracardiac volumes are the dominant triggers; the precursors are synthesised in the ventricular and atrial myocardium.<Cite n={2} /> BNP binds to natriuretic peptide receptors A and C, causing diuresis, natriuresis and vasodilation.<Cite n={3} />

The half-life of BNP is about 20 minutes and that of NT-proBNP about 120 minutes; NT-proBNP is much more stable.<Cite n={3} /> BNP, NT-proBNP and MR-proANP have comparable diagnostic and prognostic accuracy.<Cite n={2} /> Natriuretic peptide concentrations also have high prognostic accuracy for death and heart failure hospitalisation.<Cite n={2} />

</Student>

<HeartModel highlight={['left-ventricle', 'right-ventricle']} />

## When it is done

<Patient>

UK NICE guidelines recommend measuring NT-proBNP in adults who are suspected of having chronic heart failure.<Cite n={1} /> The test helps decide how urgently someone needs to see a specialist and have a [heart ultrasound (echocardiography)](../echocardiography/).<Cite n={1} />

</Patient>

<Student>

NG106 (recommendation 1.2.2): measure NT-proBNP in people with suspected heart failure.<Cite n={1} /> According to StatPearls, the primary indication for BNP measurement is distinguishing between cardiogenic and non-cardiogenic causes of dyspnoea.<Cite n={3} /> The HFA position paper notes that cut-offs for diagnosing acute heart failure are higher than those for chronic heart failure.<Cite n={2} />

</Student>

## How it is done

<Patient>

It is a blood test from a vein, like any routine blood draw.<Cite n={3} /> Your doctor or the laboratory will tell you how to prepare: follow their instructions.

</Patient>

<Student>

BNP is labile: it should be collected in EDTA tubes and ideally tested within 4 hours; serum and citrated or heparinised plasma cannot be used for BNP.<Cite n={3} /> NT-proBNP can be tested in serum and in plasma collected in heparin or EDTA.<Cite n={3} /> NT-proBNP can be kept refrigerated for up to 3 days.<Cite n={3} />

</Student>

## What the results mean

<Patient>

UK NICE guidelines use the NT-proBNP level in adults who have symptoms and whose doctor suspects heart failure, to decide how quickly to refer them to a specialist.<Cite n={1} /> These are thresholds for the urgency of referral, not "normal ranges" for the test, and they are not meant for checking healthy people without symptoms.<Cite n={1} /> When the level is very high, NICE advises urgent referral, because very high values carry a worse prognosis.<Cite n={1} /> When the level is below the threshold, the doctor looks for other causes of the symptoms and, if concern remains, discusses it with a heart failure specialist.<Cite n={1} />

A very low level makes heart failure unlikely, but a normal result does not rule it out completely.<Cite n={2} /> For example, if symptoms came on suddenly, the level may still be relatively low in the first hours; it can also be lower than expected in people with obesity.<Cite n={2} />

BNP and NT-proBNP are different measurements: one cannot be converted into the other, and they have different normal ranges and thresholds.<Cite n={2} /> Results from different laboratory methods are also hard to compare, so the normal range on the report depends on the laboratory, and the result is interpreted by a doctor.<Cite n={3} />

A raised level does not say why the heart is under strain: that needs tests of the heart, above all an ultrasound scan.<Cite n={2} /> What a particular result means is decided by a doctor, together with the other findings.<Cite n={2} />

</Patient>

<Student>

The NT-proBNP thresholds in NICE NG106 (recommendations 1.2.3–1.2.6) apply to adults with symptoms and suspected chronic heart failure and set the urgency of referral for specialist assessment and echocardiography. They are not reference values and not screening thresholds.<Cite n={1} />

| NT-proBNP | Action in NG106 |
|---|---|
| above 2,000 ng/litre (236 pmol/litre) | urgent referral: specialist assessment and transthoracic echocardiography within 2 weeks |
| 400–2,000 ng/litre (47–236 pmol/litre) | specialist assessment and transthoracic echocardiography within 6 weeks |
| below 400 ng/litre | review alternative causes for symptoms; if there is still concern, discuss with a physician with subspecialty training in heart failure |

The NG106 thresholds apply to NT-proBNP; the guideline gives no thresholds for BNP.<Cite n={1} /> A raised natriuretic peptide level must always be interpreted together with cardiac imaging, because natriuretic peptides cannot identify the underlying cause of heart failure.<Cite n={2} />

</Student>

## What affects the level

<Patient>

The level can be lower than expected in people with obesity, in people of African or African–Caribbean family background, and in people taking some medicines, such as diuretics ("water tablets").<Cite n={1} /> A raised level is not always due to heart failure: it can also be raised, for example, in people over 70, with reduced kidney function, with diabetes or with chronic obstructive pulmonary disease.<Cite n={1} />

</Patient>

<Student>

NG106 (recommendation 1.2.7) lists factors that can reduce natriuretic peptide levels: obesity, African or African–Caribbean family background, and treatment with diuretics, angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, angiotensin II receptor blockers (ARBs) and mineralocorticoid receptor antagonists (MRAs).<Cite n={1} /> Causes of high levels other than heart failure: age over 70 years, left ventricular hypertrophy, ischaemia, tachycardia, right ventricular overload, hypoxaemia (including pulmonary embolism), renal dysfunction (eGFR less than 60 ml/minute/1.73 m²), sepsis, COPD, diabetes and cirrhosis of the liver.<Cite n={1} />

People with obesity have lower concentrations, so the HFA recommends lower cut-off concentrations for them.<Cite n={2} /> [Atrial fibrillation](../../disease/atrial-fibrillation/) and atrial flutter are associated with higher concentrations.<Cite n={2} /> Sacubitril/valsartan seems to affect the concentration of BNP, which is cleared by neprilysin, so the HFA considers NT-proBNP the preferred biomarker to quantify heart failure severity.<Cite n={2} />

</Student>

## Limitations

<Patient>

The test does not show which disease is putting the heart under strain, so a raised level needs further tests of the heart.<Cite n={[2, 3]} /> Raised levels occur in many conditions, both heart-related and not.<Cite n={3} />

</Patient>

<Student>

StatPearls states that BNP should not be used as a stand-alone test when guiding therapy, and it has not been well established that BNP-guided therapy improves outcomes compared with symptom-guided therapy.<Cite n={3} /> The HFA lists situations in which concentrations are lower than expected despite heart failure: abrupt onset of symptoms (for example, within one hour), mitral stenosis and acute mitral regurgitation, pericardial constriction and tamponade, and obesity.<Cite n={2} /> Natriuretic peptide levels should be interpreted in light of renal function and body mass index.<Cite n={2} />

</Student>

## When to call an ambulance

If you suddenly become very short of breath, have chest pain or faint, call your local emergency number (112 in the EU, 911 in the US and Canada, 999 in the UK). Do not wait for a test or appointment.

<Quiz />