BNP Unit Converter
BNP Unit Converter
Convert BNP between pg/mL, ng/L and pmol/L, and see why BNP and NT-proBNP are different molecules that cannot be read against each other’s thresholds.
BNP converter
Mass ⇄ molarBNP 320 pg/mL
Formula and conversion factor
pg/mL = pmol/L ÷ 0.2887
- 0.2887
- derived from the molecular weight of BNP-32, the biologically active peptide, 3464 Da
- ng/L
- numerically identical to pg/mL
- NT-proBNP
- a different molecule with its own reference ranges — not interchangeable with BNP despite the shared name
Worked example
BNP 320 pg/mL
320 × 0.2887 = 92.4 pmol/L
= 320 ng/L, numerically identical to pg/mL
Rule-out thresholds and confounders
| Factor | Effect |
|---|---|
| Non-acute setting | Heart failure unlikely below 35 pg/mL |
| Acute breathlessness | Heart failure unlikely below 100 pg/mL |
| Age, atrial fibrillation, renal impairment, female sex | Raise BNP independent of cardiac function |
| Obesity | Lowers BNP — a normal result does not exclude heart failure |
| Sacubitril/valsartan | Raises BNP via neprilysin inhibition — trend NT-proBNP instead |
What BNP measures, and where it is misread
B-type natriuretic peptide is secreted by ventricular myocytes in response to wall stress, and its main clinical role is ruling heart failure in or out in a patient presenting with breathlessness. The distinction between pg/mL and ng/L is trivial — they are numerically identical — but the distinction between BNP and NT-proBNP is not, and the two names are used interchangeably far too often. They are different molecules, cleared by different routes, with different reference ranges, and a BNP result cannot be read against an NT-proBNP threshold or the reverse.
Interpretation depends heavily on context. In the non-acute setting a BNP below 35 pg/mL makes heart failure unlikely; in acute breathlessness the rule-out threshold rises to 100 pg/mL, because acute haemodynamic stress raises the baseline. Levels also rise with age, atrial fibrillation and renal impairment independent of cardiac function, and — in the other direction — are lowered by obesity, so a normal result in a very obese patient does not exclude heart failure and should be interpreted cautiously alongside the rest of the clinical picture.
Treatment with sacubitril/valsartan complicates BNP specifically. The drug inhibits neprilysin, the enzyme that normally degrades BNP, so BNP rises on treatment even as the patient improves, while NT-proBNP — which is not a neprilysin substrate — continues to fall. In any patient established on sacubitril/valsartan, NT-proBNP is the marker to trend; a rising BNP in that context reflects the drug, not worsening disease.
Frequently asked questions
How do I convert BNP from pg/mL to pmol/L?
Multiply by 0.2887. A BNP of 320 pg/mL is 92.4 pmol/L. pg/mL and ng/L are numerically identical, so no conversion is needed between those two.
Is BNP the same as NT-proBNP?
No. They are different molecules — BNP is the active hormone, NT-proBNP the inactive fragment cleaved alongside it — with different clearance routes and different reference ranges. Results are not interchangeable between the two.
Why might BNP be normal in a patient with heart failure?
Obesity lowers BNP independent of cardiac status, so a normal result in a markedly obese patient does not exclude heart failure. The rule-out threshold also depends on whether the presentation is acute or non-acute.
Why does BNP rise on sacubitril/valsartan?
The drug inhibits neprilysin, the enzyme that degrades BNP, so BNP rises on treatment even as heart failure improves. NT-proBNP is not affected and should be used to monitor these patients instead.
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References
- McDonagh TA et al. 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J. 2021;42(36):3599–3726.
- Mueller C et al. Heart Failure Association of the ESC practical guidance on the use of natriuretic peptide concentrations. Eur J Heart Fail. 2019;21(6):715–31.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/