Template:BNP value

Brain natriuretic peptide (BNP)

• Biologically active metabolite of proBNP (released from ventricles in response to increased volume/pressure)
• Utility is controversial and may not affect patient centered outcomes
• May be trended to gauge treatment response in acute decompensated CHF
• May have false negative with isolated diastolic dysfunction
• Measurement
  • <100 pg/mL: Negative for acute CHF (Sn 90%, NPV 89%)
  • 100-500 pg/mL: Indeterminate (Consider differential diagnosis and pre-test probability)
  • >500 pg/mL: Positive for acute CHF (Sp 87%, PPV 90%)

NT-proBNP

• N-terminal proBNP (biologically inert metabolite of proBNP)
• <300 pg/mL → CHF unlikely
• CHF likely in:
  • >450 pg/mL in age < 50 years old
  • >900 pg/mL in 50-75 years old
  • >1800 pg/mL in > 75 years old

Differential Diagnosis (Elevated BNP)

• CHF/ACS/Cardiogenic shock
• PE
• Pulmonary Hypertension
• Renal Failure
• LVH
• Subarachnoid hemorrhage

BNP In Obese Patients

• Visceral fat expansion leads to increased clearance of active natriuretic peptides
• Obese patients also frequently treated for hypertension or coronary artery disease which may also contribute to lower BNP levels

Interpretation

• In one study of 204 patients with acute CHF, an inverse relationship between BMI and BNP was noted. The standard cutoff of 100pg/mL resulted in a 20% false-negative rate
• Analysis of a subgroup of patients with documented BMI from the Breathing Not Properly study showed that a lower cutoff was more appropriate to maintain 90% sensitivity in obese and morbidly obese patients (54pg/mL)