Bedside Snapshot
- Normal (Adult)
- Acute dyspnea, heart failure (HF) unlikely: BNP <100 pg/mL; NT-proBNP <300 pg/mL
Non-acute: BNP <35 pg/mL; NT-proBNP <125 pg/mL (pg/mL = ng/L) - Critical Values
- No universal critical value: interpret by trend and clinical context. HF likely: BNP >400; NT-proBNP >450 (<50 y), >900 (50–75 y), >1,800 pg/mL (>75 y)
- High Suggests
- Acute or chronic HF
- Acute coronary syndrome (ACS), pulmonary embolism (PE), pulmonary hypertension
- Atrial fibrillation (AF), valve disease, kidney dysfunction
- Sepsis, subarachnoid hemorrhage, advanced age
- Low Suggests
- HF unlikely: look for another cause of dyspnea. Falsely low in obesity, flash pulmonary edema (onset <1 h), mitral stenosis, acute mitral regurgitation, constriction or tamponade
- Act Now If
- Dyspnea with hypoxia, hypotension or ischemic ECG: treat the clinical picture per protocol, get a 12-lead and troponin, consider PE; notify receiving/medical control. Never wait for the result
- Watch Out For
- Sacubitril/valsartan (Entresto) raises BNP: use NT-proBNP. Obesity lowers both, so a normal value does not exclude HF in a congested patient
Reference & Critical Ranges
Lab-specific ranges: Every lab sets its own range, by analyzer and by population. Use the range printed on your report. The values below are typical.
Reference ranges
| Population | Conventional | SI | Notes |
|---|---|---|---|
| Adult, non-acute (outpatient) | BNP <35 pg/mL; NT-proBNP <125 pg/mL | BNP <35 ng/L; NT-proBNP <125 ng/L | Upper limit of normal outside the acute setting in the HFA 2019 practical guidance (HFA 2019 practical guidance). Below these values heart failure (HF) is unlikely. |
| Adult, acute dyspnea | BNP <100 pg/mL; NT-proBNP <300 pg/mL | BNP <100 ng/L; NT-proBNP <300 ng/L | Rule-out thresholds for acute HF. The negative predictive value is assay-specific; confirm the figure against the source for your assay before quoting it. |
| Older adult | Values rise with age | — | Same rule-out thresholds; age-adjusted NT-proBNP rule-in (below). |
| Pregnancy | No separate guideline interval | — | Use adult thresholds with caution; levels can rise in preeclampsia. Confirm suspected HF with echocardiography. |
| Neonate (0–28 d) | NT-proBNP 260–13,224 pg/mL in healthy neonates in the first days of life | Same numbers in ng/L | Reported study range, assay-dependent; confirm with the local pediatric lab. Physiologic surge after birth, then a steady fall through the neonatal period. Adult cut-offs do not apply. |
| Infant (1–12 mo) | NT-proBNP 5–1,121 pg/mL | Same numbers in ng/L | Reported study range, assay-dependent; confirm with the local pediatric lab. Wide normal spread; use age-specific pediatric intervals. |
| Child and adolescent | Falls through childhood (median NT-proBNP about 70 pg/mL at 2–6 y, 34 pg/mL at 14–18 y) | Same numbers in ng/L | Reaches adult values around age 18. No validated pediatric HF cut-offs. |
Severity & critical values
| Level | BNP | NT-proBNP | What it means |
|---|---|---|---|
| HF unlikely | <100 pg/mL | <300 pg/mL (any age) | Very high negative predictive value. Look for another cause of dyspnea. |
| Gray zone | 100–400 pg/mL | 300–450 (<50 y); 300–900 (50–75 y); 300–1,800 pg/mL (>75 y) | About 20% of dyspneic patients; about half of them have acute HF. Weigh HF history, jugular venous pressure (JVP) and prior diuretic use; get chest imaging and echo. |
| HF likely | >400 pg/mL | >450 (<50 y); >900 (50–75 y); >1,800 pg/mL (>75 y) | High positive predictive value once confounders (renal failure, AF, PE, sepsis) are considered. |
| Critical | None defined | None defined | No panic value. The number reflects ventricular wall stress, not oxygenation or perfusion. |
| Level | BNP | NT-proBNP | What it means |
|---|---|---|---|
| HF unlikely | <35 pg/mL | <125 pg/mL (any age) | Normal; HF unlikely. |
| HF possible | 35–150 pg/mL | ≥125 (<50 y); ≥250 (50–74 y); ≥500 pg/mL (≥75 y) | Age-adjusted NT-proBNP rule-in from the HFA 2023 consensus and the 2026 ESC heart failure guideline. Arrange echocardiography. |
| HF likely / high risk | >150 pg/mL | >2,000 pg/mL | BNP >150: HF likely in the non-acute setting per HFA 2019 (HFA 2019, Table 2). NT-proBNP >2,000: associated with about a two-fold higher risk of HF hospitalization in primary care data; prioritize echocardiography and specialist review (HFA 2023 consensus). |
Critical values: None. There is no universal panic value for BNP or NT-proBNP, so read the trend and the clinical picture. A very high value does not by itself make the patient unstable. A low value does not clear them of PE, ACS or sepsis.
Conversion: 1 pg/mL = 1 ng/L. The number does not change. BNP and NT-proBNP are different molecules with different cut-offs. Never apply a BNP threshold to an NT-proBNP result.
Causes of Abnormal Results
High (BNP >100 or NT-proBNP >300 pg/mL in acute dyspnea; BNP >35 or NT-proBNP >125 pg/mL outside the acute setting)
| Mechanism | Common causes | Bedside clue |
|---|---|---|
| Ventricular volume or pressure overload | Acute decompensated HF (reduced or preserved ejection fraction); chronic HF | Orthopnea, crackles, raised JVP, edema, B-lines on ultrasound |
| Myocardial injury | Acute coronary syndrome (ACS), myocarditis, heart contusion, cardioversion or ICD shock, cardiac surgery | Chest pain, ischemic ECG, rising troponin |
| Right ventricular strain | Pulmonary embolism (PE), pulmonary hypertension, COPD with cor pulmonale | Hypoxia with clear lungs, tachycardia, dilated RV on ultrasound |
| Structural heart disease | Valve disease, left ventricular hypertrophy, hypertrophic or restrictive cardiomyopathy, congenital heart disease | Murmur, known history, echo findings |
| Arrhythmia | Atrial fibrillation (AF) or flutter, ventricular tachyarrhythmias | Irregular or rapid rhythm on the monitor |
| Reduced clearance | Chronic kidney disease (CKD), acute kidney injury, dialysis | Raised creatinine; NT-proBNP rises more than BNP |
| Systemic illness | Sepsis and severe infection including pneumonia, severe burns, anemia, thyrotoxicosis, diabetic ketosis, cirrhosis with ascites, paraneoplastic syndrome | Fever, raised lactate, abnormal thyroid tests, ascites |
| Neurologic and age-related | Subarachnoid hemorrhage, ischemic stroke; advanced age | Focal deficit, sudden severe headache; older patient with comorbidities |
Not specific for HF: A high value shows cardiac wall stress. It does not tell you the cause. A dyspneic patient with a high result still needs ACS, PE and sepsis worked through before you settle on heart failure.
Low (below the rule-out thresholds)
A low value is the most useful result. In acute dyspnea it makes HF unlikely. Look for pneumonia, COPD or asthma, PE, anemia or another cause. A few conditions give a lower value than you would expect, even when HF is present:
| Mechanism | Common causes | Bedside clue |
|---|---|---|
| Obesity | BMI ≥30 kg/m²; values fall as BMI rises | Clear signs of congestion despite a normal result |
| Very early presentation | Flash pulmonary edema; symptoms that began within about 1 hour | Abrupt onset, often with severe hypertension |
| Obstruction upstream of the left ventricle | Mitral stenosis, acute mitral regurgitation | New or loud murmur, pulmonary edema |
| Pericardial restraint | Constrictive pericarditis, cardiac tamponade | Raised JVP, pulsus paradoxus, effusion on ultrasound |
A normal result does not override the exam: In obese patients and in flash pulmonary edema, a reassuring value can still come with heart failure. Treat the clinical picture. If doubt remains, repeat the test or image the heart.
Interpretation & Bedside Approach
Step-by-step approach
- Confirm which test and setting: Check BNP or NT-proBNP, the acute or non-acute threshold, and that the units match (pg/mL = ng/L). On sacubitril/valsartan (Entresto), use NT-proBNP. The drug raises BNP.
- Judge how sick the patient is: The peptide backs up the exam, the ECG, chest imaging and ultrasound. It never replaces them. Respiratory distress gets treated now, not after a result comes back.
- Compare with the baseline: In known HF, compare against the stable (dry) value. The 2023 HFA/HFSA/JHFS statement describes a rise of 25–30% or more from that value as suggesting decompensation. Biological variability is about 25% for NT-proBNP and 40% for BNP. For BNP, a rise within about 40% may be noise, and smaller changes may be biological noise too.
- Adjust for confounders: Age, obesity, kidney function, AF and sacubitril/valsartan all shift the result. The table below shows how.
- Classify with current thresholds: Apply the acute cut-offs of HFA 2019, or the non-acute cut-offs of HFA 2019 with the age-adjusted NT-proBNP rule-in from HFA 2023 and the 2026 ESC guideline. The ranges sit in Reference & Critical Ranges. A gray-zone result calls for chest imaging and echocardiography.
- Escalate or dispose: A high value with an HF picture calls for echocardiography and cardiology input. Higher admission and predischarge values carry a higher risk of death and readmission.
Adjusting for common confounders
| Factor | Effect | How to adjust |
|---|---|---|
| Age | ↑ with age, driven largely by comorbidities | Rule-out thresholds unchanged; use age-adjusted NT-proBNP rule-in thresholds |
| Obesity (BMI ≥30 kg/m²) | ↓ BNP and NT-proBNP | Acute: lower cut-offs by up to 50% (BNP rule-out <50 pg/mL). Non-acute NT-proBNP rule-in: lower by 25%, 30% and 40% for obesity class I, II and III |
| eGFR <60 mL/min | ↑, NT-proBNP more than BNP | BNP rule-out 200 pg/mL instead of 100, per the HFA 2019 practical guidance. For NT-proBNP, that guidance sees no added adjustment once age-adjusted rule-in thresholds are used, but the HFA 2023 consensus proposes raising the cut-off by 15–35% as eGFR falls below 60 (expert opinion); interpret with caution. |
| Dialysis | ↑, unpredictable | NP testing to diagnose HF is discouraged; follow the patient's own trend |
| Atrial fibrillation | ↑ even without HF | No separate cut-off. AF raises both peptides even without HF; with new dyspnea and AF, do not rely on a mildly raised value alone and do not dismiss HF. Assess with echocardiography. |
| Sacubitril/valsartan | BNP ↑ or unchanged; NT-proBNP ↓ about 30% | Monitor with NT-proBNP |
Guideline uses (2022 AHA/ACC/HFSA)
- Dyspnea: BNP or NT-proBNP helps support or exclude HF in the dyspneic patient (Class 1).
- Chronic HF and hospital admission: use it to stratify risk and judge prognosis (Class 1).
- Before discharge: a predischarge value helps set the post-discharge prognosis (Class 2a).
- At-risk patients (Stage A): NP screening followed by team-based care can help prevent LV dysfunction or new HF (Class 2a).
- NP-guided titration: there is no proven benefit. The GUIDE-IT trial of NT-proBNP-guided therapy came back neutral.
Field & Transport Considerations
Point-of-care testing
Point-of-care BNP and NT-proBNP immunoassays exist in many emergency departments. Results are assay-specific, so write down which peptide and which device gave the number. They do not steer prehospital care. In EMS, treat suspected cardiogenic pulmonary edema on the picture in front of you: work of breathing, lung sounds, SpO₂, waveform EtCO₂, the 12-lead ECG and, where available, ultrasound. Treat per local protocol. High-dose nitrate and noninvasive ventilation for cardiogenic pulmonary edema depend on protocol, so follow local medical direction.
Before and during interfacility transport
| Setting | Consideration |
|---|---|
| Handover data | Value with time and assay (BNP or NT-proBNP), the patient's stable baseline if known, creatinine/eGFR, troponin, echo result and whether the patient takes sacubitril/valsartan. |
| En route | Values fall over hours to days with decongestion; there is no reason to repeat a level during transport. Track response with respiratory effort, SpO₂, blood pressure and urine output. |
| Destination decisions | A high value alone should not delay or redirect transport; clinical status, ECG and suspected cause (ACS, PE, decompensated HF) drive the destination. |
Timing & Kinetics
| Parameter | Value | Clinical implication |
|---|---|---|
| Very early presentation | May be low if symptoms began within about 1 hour | Flash pulmonary edema can show a falsely reassuring value; repeat later if doubt remains. |
| Half-life, BNP | About 20 min | Tracks the current hemodynamic state more closely. |
| Half-life, NT-proBNP | About 120 min; cleared mainly by the kidneys | Circulating values run higher than BNP and rise further as eGFR falls. |
| Biological variability | About 25% (NT-proBNP) and 40% (BNP) | Changes smaller than this between two results may be noise. |
| When to draw | At presentation with new or worsening dyspnea or fatigue; again before discharge | Admission and predischarge values both predict death and readmission. |
| During admission | Expect a fall of more than about 30% with effective decongestion | 37–47% of patients do not reach it; they are a higher-risk group. |
| After starting sacubitril/valsartan | NT-proBNP falls about 30%; BNP rises slightly or stays flat | Use NT-proBNP to judge response. |
Know the dry value: Record each HF patient's stable value before you need it. When they come back short of breath, compare against that number, not the population cut-offs.
Special Populations
| Population | What changes | Clinical implication |
|---|---|---|
| Neonates & infants | Very high in the first days of life after the circulatory transition, then a steady fall through the neonatal period and infancy | Adult cut-offs do not apply; use age-specific intervals. Used in neonatal care, including assessment of a patent ductus arteriosus. |
| Children & adolescents | Values fall through childhood and reach adult levels around age 18 | Used to monitor congenital heart disease and cardiomyopathy and to assess cardiac involvement in Kawasaki disease and multisystem inflammatory syndrome in children (MIS-C). No validated pediatric HF cut-offs. |
| Pregnancy | No separate guideline interval; values can rise in preeclampsia | Dyspnea and edema are common in late pregnancy; a raised value supports echocardiography to look for peripartum cardiomyopathy or other heart disease. |
| Older adults | Values rise with age, largely from comorbidities | Keep the rule-out thresholds; use age-adjusted NT-proBNP rule-in thresholds. |
| CKD / dialysis | Reduced clearance raises both, NT-proBNP more | eGFR <60: BNP rule-out 200 pg/mL. On dialysis, NP testing to diagnose HF is discouraged; use the patient's own trend. |
| Liver disease | Cirrhosis with ascites raises values | Interpret with the volume exam and echocardiography. |
| Other | Obesity lowers values; women run slightly higher than men | Lower thresholds in obesity; no sex-specific cut-offs. |
Interfering Factors & Pitfalls
Collection & handling
| Factor | Effect | Why | Avoid / fix |
|---|---|---|---|
| Wrong tube | Rejected or unreliable result | BNP assays use EDTA whole blood or plasma; NT-proBNP assays accept serum or plasma, depending on the analyzer | Use the tube your lab specifies for the ordered peptide |
| Switching analyzers | ↑ or ↓ | BNP assays from different manufacturers are not standardized | Trend results from the same lab and assay |
Medications & supplements
| Factor | Effect | Why | Avoid / fix |
|---|---|---|---|
| Sacubitril/valsartan | ↑ BNP (or unchanged); ↓ NT-proBNP | BNP is a neprilysin substrate; NT-proBNP is not | Use NT-proBNP for diagnosis and monitoring |
| Decongestion and guideline-directed therapy | ↓ | Diuretics, ARNI and SGLT2 inhibitors lower wall stress | Note recent therapy when comparing with earlier values |
Physiologic / biologic
Age, obesity (false −), kidney dysfunction, AF and very early presentation (onset under 1 hour, false −) all shift results. The confounder table in Interpretation & Bedside Approach and the low-value table in Causes of Abnormal Results show how.
Common misinterpretations
- Higher means sicker right now: No. The number reflects wall stress and prognosis. It does not measure respiratory or hemodynamic stability.
- BNP and NT-proBNP are interchangeable: No. Cut-offs differ several-fold, and sacubitril/valsartan distorts BNP.
- A normal value excludes HF in every patient: Not in obesity, flash pulmonary edema, mitral disease or pericardial constriction. Those patients can have heart failure with a normal value.
- Serial values should guide diuretic dosing: NP-guided titration has not improved outcomes. Use the clinical response instead.
Do not chase the number: Stays high after good diuresis? That may be this patient's new stable level. Let the exam and hemodynamics tell you the volume status.
Physiology & Test Basics
What it measures
This page covers B-type natriuretic peptide (BNP) and its inactive N-terminal fragment (NT-proBNP). You measure them in blood to diagnose heart failure and to stratify its risk. The old name "brain natriuretic peptide" is a misnomer. Both come mainly from the cardiac ventricles. They are separate tests with separate cut-offs.
Physiology & regulation
- Trigger: ventricular wall stress from volume or pressure overload sets it off.
- Processing: the precursor proBNP is cut into active BNP and inactive NT-proBNP. Both go into the circulation together.
- Actions of BNP: BNP drives natriuresis and diuresis and widens the vessels. It suppresses the renin-angiotensin-aldosterone and sympathetic systems. In the heart, it has antihypertrophic and antifibrotic effects.
- Clearance of BNP: the clearance receptor NPR-C and the enzyme neprilysin remove it.
- Clearance of NT-proBNP: Mainly the kidneys clear it. As eGFR falls, it builds up.
How it is measured
It is an immunoassay on venous blood. BNP goes in EDTA (lavender-top) whole blood or plasma. NT-proBNP goes in serum or plasma, depending on the analyzer. No fasting needed. Point-of-care and central-lab platforms both run it. Results come back in pg/mL, identical to ng/L.
Why it matters
In acute dyspnea, a value under the rule-out threshold makes heart failure unlikely. It sends the workup somewhere else. In known HF, admission and predischarge values are among the strongest predictors of death and readmission.
Clinical Pearls
Best as a rule-out test: Its strength is ruling out. In acute dyspnea, BNP <100 or NT-proBNP <300 pg/mL makes heart failure unlikely. Go looking for pneumonia, COPD, PE or another cause.
Entresto changes BNP: Sacubitril/valsartan blocks the breakdown of BNP, so BNP climbs. NT-proBNP falls as the heart improves. In these patients, order and trend NT-proBNP.
Age the NT-proBNP rule-in: A value of 950 pg/mL is in the HF-likely range at 45 but in the gray zone at 80. The rule-out value (<300 pg/mL) does not move with age.
Obesity hides heart failure: Values fall as BMI rises. An obese patient with crackles, a raised JVP and edema can have heart failure with a normal result.
Transport: Don't wait for a level, and don't repeat one en route. Hand over the value, the time drawn, the assay and any known baseline. Manage the patient on the exam and the monitor.
Nursing trend: Pair the peptide result with daily weight and intake and output. Patients with marked right-sided congestion, such as ascites or heavy edema, may lose liters of fluid before the value falls.
References
- Tsutsui, H., Albert, N. M., Coats, A. J. S., Anker, S. D., et al. (2023). Natriuretic peptides: Role in the diagnosis and management of heart failure: A scientific statement from the Heart Failure Association of the European Society of Cardiology, Heart Failure Society of America and Japanese Heart Failure Society. European Journal of Heart Failure, 25(5), 616–631. https://doi.org/10.1002/ejhf.2848
- Heidenreich, P. A., Bozkurt, B., Aguilar, D., Allen, L. A., et al. (2022). 2022 AHA/ACC/HFSA guideline for the management of heart failure. Circulation, 145(18), e895–e1032. https://doi.org/10.1161/CIR.0000000000001063
- European Society of Cardiology. (2026). 2026 ESC Guidelines for the management of heart failure. European Heart Journal, 47(38), 5346. https://doi.org/10.1093/eurheartj/ehag100
- Mueller, C., McDonald, K., de Boer, R. A., Maisel, A., et al. (2019). Heart Failure Association of the European Society of Cardiology practical guidance on the use of natriuretic peptide concentrations. European Journal of Heart Failure, 21(6), 715–731. https://doi.org/10.1002/ejhf.1494
- Bayes-Genis, A., Docherty, K. F., Petrie, M. C., Januzzi, J. L., et al. (2023). Practical algorithms for early diagnosis of heart failure and heart stress using NT-proBNP: A clinical consensus statement from the Heart Failure Association of the ESC. European Journal of Heart Failure, 25(11), 1891–1898. https://doi.org/10.1002/ejhf.3036
- Novartis Pharmaceuticals Corporation. (2026). Entresto (sacubitril and valsartan) tablets and oral pellets: Prescribing information. DailyMed, U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=000dc81d-ab91-450c-8eae-8eb74e72296f
- Alcidi, G., Goffredo, G., Correale, M., Brunetti, N. D., & Iacoviello, M. (2022). Brain natriuretic peptide biomarkers in current clinical and therapeutic scenarios of heart failure. Journal of Clinical Medicine, 11(11), 3192. https://doi.org/10.3390/jcm11113192
- Ludwikowska, K. M., Tokarczyk, M., Paleczny, B., Tracewski, P., et al. (2024). Clinical significance of B-type natriuretic peptide and N-terminal pro-B-type natriuretic peptide in pediatric patients: Insights into their utility in the presence or absence of pre-existing heart conditions. International Journal of Molecular Sciences, 25(16), 8781. https://doi.org/10.3390/ijms25168781
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