PURPOSE: Serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) are often increased in patients with impaired renal function. The objective of this study was to investigate whether the increase in NT-proBNP is predominantly due to a reduced renal clearance or an increased cardiac secretion.
METHODS: A series of 697 outpatients (57.5 ± 16.4 years) referred for evaluation of dyspnea were assigned to 4 groups according to their estimated glomerular filtration rate [eGFR (ml/min per 1.73 m2)]: group 1, eGFR <60 (n=77); group 2, eGFR ≥60-75 (n=139); group 3, eGFR ≥75-90 (n=191); and group 4, eGFR ≥ 90 (n=289). The patients were also grouped into 2 categories based on the presence (n=176) or absence (n=521) of heart disease.
RESULTS: In patients without heart disease, eGFR group 1 membership had no effect on NT-proBNP both in the entire cohort and in the subgroup of patients with NT-proBNP levels in the highest quartile. In patients with heart disease, the values for NT-proBNP were higher in eGFR group 1 than in eGFR groups 2, 3 and 4 after adjustment for the type of heart disease and important extracardiac covariates (p<0.01).
CONCLUSIONS: A reduced renal clearance does not explain increased NT-proBNP levels in patients with moderate renal impairment and dyspnea. Rather, our data suggest that a moderate reduction of renal function places additional stress on the heart in patients with established cardiac disease.
CLINICAL IMPLICATIONS: This kidney-mediated excess burden of stress may further reduce the exercise tolerance and contribute to the increased cardiovascular risk of cardiac disease patients with at least moderate renal dysfunction.
DISCLOSURE: The following authors have nothing to disclose: Siegfried Wieshammer, Jens Dreyhaupt
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