Influence of renal function on N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients admitted for dyspnoea in the Emergency Department: Comparison with brain natriuretic peptide (BNP)

Backgrounds: Renal dysfunction influences the optimum brain natriuretic peptide (BNP) threshold for a diagnosis of cardiac-related dyspnoea, but this has not been demonstrated for N-terminal pro-brain natriuretic peptide (NT-proBNP). We studied the influence of renal function on NT proBNP and BNP concentrations in dyspnoeic patients admitted by night to the Emergency Department (ED). Methods: NT-proBNP, BNP, and creatinine levels were measured in blood samples collected routinely from 381 patients; estimated glomerular filtration rate (eGFR) was calculated. Results: Cardiac-related dyspnoea was found in 115 patients (30.2%). NT-proBNP and BNP values were elevated in patients with cardiac-related dyspnoea (6823 +/- 6569 vs. 2716 +/- 4838 pg/ml, and 642 +/- 329 vs. 243 +/- 267 pg/ml, p <0.0001, respectively). Log-transformed NT-proBNP and BNP values were correlated to eGFR values. Mean NT-proBNP and BNP values stratified by ED diagnosis increased in line with eGFR categories, but in each category both peptide concentrations remained elevated in cardiac-related dyspnoea when compared with non-cardiac-related dyspnoea (p<0.05). NT-proBNP (and BNP) cut-off points rose as a function of eGFR categories: from 1360 (and 290) pg/ml in patients with eGFR 60-89 ml/min/1.73 m(2), to 6550 (and 515) pg/ml in patients with eGFR 15-29 ml/min/1.73 m(2). Conclusion: Renal function influences the optimal cut-off points of NT-proBNP and BNP for the diagnosis of cardiac-related dyspnoea. (c) 2005 Elsevier B.V. All rights reserved.