Plasma B-type natriuretic peptide in dialyzed patients: Marker of cardiovascular disease or link to plasma refilling?

Background: B-type natriuretic peptide (BNP) is released in response to extracellular volume and blood pressure (BP) overload and is a risk factor for cardiovascular diseases (CVD). BNP is increased in dialyzed patients (HDpts). The aim of this study was to evaluate the relationships between BNP and renin, aldosterone and blood volume reduction rate (BV/WL), with the presence of CVD and mortality. Methods: Fifty-one HDpts aged 70 ± 14 years were enrolled. BP, BV/WL, BNP, aldosterone, renin, C-reactive protein (CRP), troponin I and routine biochemistry were measured. According to the predialytic plasma BNP levels, the patients were divided into group A with higher BNP and group B with lower BNP than the median value of 330 pg/mL. Follow-up was 1 year. Results: After HD, plasma BNP (449.6 ± 582.2 pg/ mL vs. 264.1 ± 269.8 pg/mL, p=0.0008) and aldosterone (421.8 ± 573.4 pg/mL vs 265.1 ± 566.2 pg/mL, p=0.0003) decreased, but not rennin. BNP decreased more after hemodiafiltration than after standard HD (-55.1% ± 28.5% vs. -26.5% ± 19.5%, p=0.002). Patients in group A exhibited more diabetes (58% vs. 28%, p=0.03), ischemic heart disease (42% vs. 16%, p=0.04), left ventricular hypertrophy (88.8% vs. 33.3%, p<0.001), elevated levels of troponin I, CRP (50% vs. 24%, p=0.05), and low BV/BWL in a lower percentage (8% vs. 32%, p=0.03). After 11.2 ± 3.5 months, 8 patients (33.3%) had died in group A and 2 (8%) in group B (p=0.02). Conclusion: This study demonstrates that BNP is high in HDpts and decreases after HD. It is correlated with a good capacity for plasma refilling, with diabetes, CVD and short-term mortality risk.