From the Guidelines
B-type natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are both cardiac biomarkers used to diagnose heart failure, but they have important differences, with NT-proBNP having a longer half-life and being more influenced by kidney disease, as noted in the 2017 study by the American College of Cardiology 1.
Key Differences
- BNP is the active hormone released by the ventricles when they're stretched due to increased pressure or volume, while NT-proBNP is the inactive fragment cleaved from the prohormone (proBNP) during BNP production.
- NT-proBNP has a longer half-life (60-120 minutes) compared to BNP (20 minutes), making it more stable in blood samples, as mentioned in the 2012 position statement from the European Society of Cardiology 1.
- Reference ranges differ significantly: BNP values above 100 pg/mL suggest heart failure, while NT-proBNP uses age-adjusted cutoffs (450 pg/mL for <50 years, 900 pg/mL for 50-75 years, and 1800 pg/mL for >75 years), as discussed in the 2007 guidelines by the National Academy of Clinical Biochemistry 1.
Clinical Implications
- NT-proBNP levels are typically numerically higher than BNP for the same degree of heart failure, as noted in the 2015 systematic review and diagnostic meta-analysis in the acute care setting 1.
- Renal function affects both markers, but NT-proBNP is more influenced by kidney disease since it's primarily cleared by the kidneys, while BNP is cleared through receptor-mediated mechanisms and neutral endopeptidases, as mentioned in the 2017 study by the American College of Cardiology 1.
- The choice between BNP and NT-proBNP should be based on the clinical context and the availability of assays, with consideration of the potential effects of renal function and other comorbidities on the results, as discussed in the 2012 position statement from the European Society of Cardiology 1.
From the Research
Difference between NT-proBNP and BNP
- NT-proBNP is a 76-amino acid biologically inert N-terminal fragment, while BNP is a biologically active 32-amino acid peptide 2
- Both peptides are synthesized by the ventricles of the heart as a 108-amino acid polypeptide precursor (proBNP), which is then cleaved into NT-proBNP and BNP 2
- The generation of BNP is enhanced in response to high ventricular filling pressures, making the measurement of either BNP or NT-proBNP useful in diagnosing congestive heart failure 2, 3
Biochemical and Pathophysiological Characteristics
- NT-proBNP is virtually resistant to enzymatic cleavage, while BNP is efficiently degraded by the enzyme neprilysin 2
- The molar ratio of NT-proBNP to BNP varies considerably according to rhythm, age, renal function, and body mass index 4, 5
- The measurement of BNP gives different, but complementary, pathophysiological and clinical information compared to NT-proBNP 6
Clinical Applications
- Both BNP and NT-proBNP are used to aid diagnosis, assess the effect of therapy, and predict outcomes in heart failure and reduced ejection fraction 4
- The measurement of NT-proBNP may be useful in patients taking neprilysin inhibitors, as BNP levels may not reliably reflect cardiac dysfunction 2
- The molar ratio of NT-proBNP to BNP may be a significant prognostic factor for heart failure-related events 5