- 01Which peptide, which setting
A BNP of 180 pg/mL is high on a routine test and above the emergency rule-out line; an NT-proBNP of 180 is only just over the routine line and below the emergency rule-out line. Read your number only against the cutoff for your peptide and your setting: BNP 35 routine and 100 emergency; NT-proBNP 125 routine and 300 emergency 1.
An elevated or high BNP means the heart's lower pumping chambers (the ventricles) are being stretched by pressure or extra fluid; the result does not say why. Two things decide what your number means: which of the two peptides your lab measured, and whether the test was done in an emergency or at a routine visit, because the cutoffs differ roughly threefold between those two settings.
Check which one is on your report
Is yours BNP or NT-proBNP?
The heart makes one precursor molecule and splits it into two pieces: BNP, the active hormone, and NT-proBNP, an inactive fragment. Together they are called natriuretic peptides (heart hormones that help the body shed salt and water). Labs measure one or the other, and the names on reports are loose; some tests sold as a "BNP test" measure NT-proBNP, and an elevated proBNP on a report almost always means NT-proBNP. NT-proBNP stays in the blood longer, one reason its numbers run several times higher 6. The units match either way: 1 pg/mL equals 1 ng/L. The full side-by-side is on <a href="/compare/bnp-vs-nt-probnp">BNP vs NT-proBNP</a>, and the marker itself on the <a href="/biomarkers/bnp">BNP marker page</a>.
| BNP | NT-proBNP | |
|---|---|---|
| What it is | Active hormone | Inactive fragment of the same precursor |
| Time in the blood | Shorter | Longer |
| Routine "raised" line | 35 pg/mL | 125 pg/mL |
| Emergency rule-out line | 100 pg/mL | 300 pg/mL |
| Raised by sacubitril/valsartan (Entresto)? | Yes | No |
What counts as high
Example: a routine BNP of 180 pg/mLpg/mL
Guidelines set BNP cutoffs by setting: one line for a routine visit, another for someone who arrives breathless, and, for a high or elevated NT-proBNP, referral bands that set how fast a person should be seen. The two tables below split them by setting.
Routine test (no emergency)
| Band | BNP (pg/mL = ng/L) | NT-proBNP (pg/mL = ng/L) | What it usually means | Usual next step |
|---|---|---|---|---|
| Below the routine line | Under 35 | Under 125 | Heart failure unlikely in someone not on heart treatment 1 | No heart-failure work-up needed for this result |
| Above the routine line | 35 or more | 125 or more (see the NICE bands below) | Raised; many causes, including age, kidneys and rhythm 1 2 | Doctor's visit; echocardiogram (heart ultrasound) considered |
| NICE 6-week band | No NICE band given | 400 to 2,000 | Heart failure possible 2 | Specialist review and echo within 6 weeks |
| NICE 2-week band | No NICE band given | Over 2,000 (over 236 pmol/L) | Heart failure more likely; worse outlook 2 | Specialist review and echo within 2 weeks |
Emergency test (someone breathless)
| Band | BNP (pg/mL = ng/L) | NT-proBNP (pg/mL = ng/L) | What it usually means | Usual next step |
|---|---|---|---|---|
| Rule-out | Under 100 | Under 300 | Breathlessness probably not from heart failure 1 | Look for another cause |
| Grey zone | 100 to 400 | Between the rule-out and rule-in lines | Heart failure not ruled out, not confirmed 6 | Echocardiogram and clinical assessment |
| Rule-in | Over 400 | Over 450 if under 50 years old; over 900 at age 50 to 75; over 1,800 over 75 | Heart failure likely 4 6 | Hospital assessment |
Example: a routine NT-proBNP of 850 pg/mLpg/mL
A BNP of 1,000 pg/mL is well above the 400 pg/mL rule-in line, and in someone with breathlessness or swelling it is strong evidence of heart strain that needs prompt assessment. In the Breathing Not Properly study of 1,586 people arriving with acute breathlessness, a BNP cutoff of 100 pg/mL sorted heart failure from other causes with about 83% accuracy 3.
When it is urgent
Urgency comes from your symptoms and from the size of the number. For NT-proBNP, the UK's NICE guideline sets the clearest line.
Because very high levels of NT-proBNP carry a poor prognosis, refer people with suspected heart failure and an NT-proBNP level above 2,000 ng/litre (236 pmol/litre) urgently, to have specialist assessment and transthoracic echocardiography within 2 weeks.NICE guideline NG106, Chronic heart failure in adults 2
How high is dangerous?
Risk climbs steadily as BNP climbs, with no single cutoff where it turns fatal. The ADHERE registry tracked 48,629 hospital admissions for heart failure and found that in-hospital death rose from 1.9% when admission BNP was under 430 pg/mL to 6.0% when it was 1,730 pg/mL or higher 5.
No guideline gives a life expectancy for an NT-proBNP of 3,000 or 10,000 pg/mL, or for any other number. Both are above NICE's 2,000 pg/mL urgent line and mark high risk 2; what happens next depends on the cause and on how the number responds to treatment, and a level that falls with treatment is a good sign 1.
Is it really high?
Several things shift BNP and NT-proBNP without any new heart disease. Check these before reading a single result as a diagnosis.
- Age: natriuretic peptides rise with age, which is why emergency NT-proBNP rule-in lines go from 450 pg/mL under 50 to 1,800 pg/mL over 75 4. NICE lists age over 70 as a raiser 2.
- Kidney function: an eGFR (estimated kidney filtration rate) below 60 slows clearance and raises the level, often moderately, without heart failure 2. Read BNP beside your <a href="/biomarkers/egfr">eGFR</a>.
- Sex: women tend to run higher than men at the same heart status 6.
- Body weight: higher body weight lowers natriuretic peptides, so a normal number in someone with obesity reassures less; the Heart Failure Association suggests cutoffs about 50% lower at a BMI of 30 or more 6.
- Heart medicines: water tablets (diuretics), blood pressure tablets such as ramipril or losartan, beta-blockers and spironolactone can all lower the level 2.
- Sacubitril/valsartan (Entresto): raises BNP because the drug blocks the enzyme that breaks BNP down, while NT-proBNP falls, so on this drug doctors usually track NT-proBNP instead 6.
- Family background: NICE notes lower levels in people of African or African-Caribbean family background 2.
- Hard endurance exercise: a marathon or long race shortly before the draw can push the level up temporarily. Our <a href="/learn/how-to-prepare-for-a-blood-test">blood test prep guide</a> covers timing.
- Dehydration: less fluid means less stretch on the heart, so dehydration is not a recognized cause of a raised BNP; extra fluid is what raises it.
BNP and NT-proBNP swing noticeably from day to day in the same person, so small changes mean little. Repeat on the same peptide at the same lab, rested, with no hard exercise the day before, and compare trends rather than single points 6.
What causes elevated BNP?
Common
| Cause | How it raises BNP | Clue | Test that checks it | Source |
|---|---|---|---|---|
| Heart failure (weak pump or stiff pump) | Fluid and pressure stretch the ventricles (the two lower pumping chambers) | Breathless on exertion or lying flat, ankle swelling | Echocardiogram; <a href="/biomarkers/nt-probnp">NT-proBNP</a> trend | 1 |
| Atrial fibrillation | Fast, irregular beats strain the atria (the two upper chambers) and the ventricles | Irregular pulse, <a href="/symptoms/heart-palpitations">palpitations</a> | <a href="/biomarkers/electrocardiogram">ECG</a>; <a href="/biomarkers/tsh">TSH</a> | 1 |
| Thickened heart muscle from long-standing high blood pressure | A stiff, thick wall raises filling pressure | Years of high readings; see <a href="/conditions/high-blood-pressure">high blood pressure</a> | Blood pressure readings; echo | 2 |
| Kidney disease | Slower clearance plus fluid retention | Low eGFR, high creatinine; see <a href="/conditions/chronic-kidney-disease">chronic kidney disease</a> | <a href="/biomarkers/creatinine-serum/high">Creatinine</a>, <a href="/biomarkers/egfr">eGFR</a> | 2 |
| Older age | Stiffer heart and lower kidney clearance | Mild rise, over 70, no symptoms | Age-adjusted cutoffs; echo if in doubt | 2 4 |
CalculatoreGFR calculatorNT-proBNP has to be read with kidney function; work out your eGFR from creatinine, age and sex.Work it out Less common
| Cause | How it raises BNP | Clue | Test that checks it | Source |
|---|---|---|---|---|
| Heart valve disease (aortic stenosis, mitral regurgitation) | Pressure or backflow overloads a chamber | Murmur heard by a doctor | Echocardiogram | 1 |
| Pulmonary hypertension and chronic obstructive pulmonary disease (COPD) | High lung pressures strain the right ventricle; low oxygen adds to it | Long-term lung disease, low oxygen | Echo; oxygen saturation | 1 2 |
| Anemia | The heart pumps harder to carry less oxygen | Tiredness, pale skin; see <a href="/conditions/anemia">anemia</a> | <a href="/biomarkers/hemoglobin">Hemoglobin</a> | 1 |
| Overactive thyroid | A faster, harder-working heart | Weight loss, tremor, fast pulse; see <a href="/conditions/hyperthyroidism">hyperthyroidism</a> | <a href="/biomarkers/tsh">TSH</a> | 1 |
| Liver cirrhosis and diabetes | Fluid shifts and heart muscle changes | Known liver disease, high A1c | Liver panel; <a href="/biomarkers/hba1c">HbA1c</a> | 2 |
Must not miss
| Cause | How it raises BNP | Red flag | Test that checks it | Source |
|---|---|---|---|---|
| Heart attack or reduced blood flow to the heart | Injured muscle stiffens and strains | Chest pain or pressure: emergency care now | <a href="/biomarkers/troponin-i-hs/high">High-sensitivity troponin</a>, ECG | 1 2 |
| Pulmonary embolism (clot in the lung) | Sudden right-ventricle overload | Sudden breathlessness, painful swollen leg: emergency care now | <a href="/biomarkers/d-dimer/high">D-dimer</a>, CT scan | 1 2 |
| Sepsis and critical illness | Inflammation and low blood pressure strain the heart | Fever with confusion or fast breathing: emergency care now | Blood cultures, <a href="/biomarkers/crp/high">CRP</a> | 1 2 |
Symptoms
BNP causes no symptoms by itself; any symptoms come from whatever is raising it. With heart failure that usually means breathlessness on exertion or lying flat, swollen ankles, weight gain over days from fluid, and tiredness. Atrial fibrillation brings <a href="/symptoms/heart-palpitations">palpitations</a> and sometimes <a href="/symptoms/dizziness">dizziness</a>; anemia and thyroid problems bring <a href="/symptoms/fatigue">fatigue</a>. A mildly raised BNP in an older person or someone with kidney disease often comes with no symptoms at all.
Read it with your other markers
The markers that sort the causes
BNP shows stretch; troponin shows injury. Read together, they tell strain from damage.
| Pattern | What it suggests | Read more |
|---|---|---|
| High BNP, normal troponin, normal eGFR | Strain from pressure or fluid; echo is the next test | <a href="/learn/cardiac-markers-explained">Cardiac markers explained</a> |
| High BNP, high troponin | Heart muscle injury as well as strain | <a href="/biomarkers/troponin-i-hs/high">High troponin</a> |
| High BNP, eGFR under 60 | Part of the rise may be slower kidney clearance | <a href="/learn/kidney-function-explained">Kidney function explained</a> |
| High BNP, low hemoglobin | Anemia adding to the heart's workload | <a href="/conditions/anemia">Anemia</a> |
| High BNP, low TSH | Overactive thyroid speeding the heart | <a href="/conditions/hyperthyroidism">Hyperthyroidism</a> |
| High BNP, high D-dimer, sudden breathlessness | Possible lung clot: emergency care | <a href="/biomarkers/d-dimer/high">High D-dimer</a> |
What usually happens next
- 1An echocardiogramAn ultrasound of the heart is the main test after a raised BNP; it shows pumping strength, wall thickness and valves. NICE sets the timing by NT-proBNP: within 6 weeks at 400 to 2,000 pg/mL, within 2 weeks above 2,000 2.
- 2An ECG and blood testsAn <a href="/biomarkers/electrocardiogram">ECG</a> checks rhythm and signs of past damage. Blood tests usually include creatinine and eGFR, a full blood count, TSH, <a href="/learn/electrolytes-explained">sodium and potassium</a>, and HbA1c, with troponin if symptoms are acute 1.
- 3A chest X-ray or other tests where neededA chest X-ray looks for fluid on the lungs; D-dimer and a CT scan follow if a lung clot is suspected.
- 4Referral to a heart specialistIf the echo or bloods show heart failure or valve disease, a cardiologist plans treatment. Guidelines recommend this blood test for anyone suspected of heart failure 1.
- 5A repeat on the same testDoctors repeat the same peptide at the same lab to see the direction of change; a falling number on treatment is reassuring 6.
What can bring it down
BNP comes down when the cause is treated and the heart is under less stretch. No food or supplement has good human evidence for lowering BNP in a way that matters, and products marketed for "heart support" have not been shown to change the number or the strain behind it. Any change to salt, fluid or medicines belongs with the doctor treating the cause. For the wider picture on keeping your heart healthy, see our <a href="/for/heart">heart hub</a>.
| Change | Effect on BNP | Evidence type | Source |
|---|---|---|---|
| Guideline heart failure treatment, run by a specialist | Levels fall as congestion clears; a falling level tracks a better outlook | Randomized trials, guideline | 1 |
| Controlling high blood pressure over time | Treats a cause that raises BNP | Guideline (listed cause) | 2 |
| Rate or rhythm control of atrial fibrillation | Treats a cause that raises BNP | Guideline (listed cause) | 1 |
| Treating anemia or an overactive thyroid | Treats a cause that raises BNP | Guideline (listed cause) | 1 |
| Supplements marketed for the heart | No reliable effect shown | No reliable human evidence | - |
BNP can also be used to find heart trouble early. In the STOP-HF trial of 1,374 people with risk factors such as high blood pressure or diabetes, a BNP of 50 pg/mL or more triggered an echocardiogram and team-based care, and fewer people went on to develop a weakened or stiff heart (with or without heart failure) than with usual care 7.
Free, no accountRead your blood testHave the full report? Read BNP beside your kidney, blood count and thyroid markers.Read my results
Citations
- McDonagh TA et al. 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J 2021;42:3599-3726.
- NICE guideline NG106: Chronic heart failure in adults: diagnosis and management. First published 2018.
- Maisel AS et al. Rapid measurement of B-type natriuretic peptide in the emergency diagnosis of heart failure. N Engl J Med 2002;347:161-167.
- Januzzi JL et al. NT-proBNP testing for diagnosis and short-term prognosis in acute destabilized heart failure: an international pooled analysis of 1256 patients (ICON). Eur Heart J 2006;27:330-337.
- Fonarow GC et al. Admission B-type natriuretic peptide levels and in-hospital mortality in acute decompensated heart failure (ADHERE). J Am Coll Cardiol 2007;49:1943-1950.
- Mueller C et al. Heart Failure Association of the European Society of Cardiology practical guidance on the use of natriuretic peptide concentrations. Eur J Heart Fail 2019;21:715-731.
- Ledwidge M et al. Natriuretic peptide-based screening and collaborative care for heart failure: the STOP-HF randomized trial. JAMA 2013;310:66-74.
Educational context only, not medical advice or a diagnosis. Always discuss your results with a clinician.
