Relative importance of residual renal function and convection in determining beta-2-microglobulin levels in high-flux haemodialysis and on-line haemodiafiltration

Background: Convective blood purification improves beta(2)-microglobulin (beta M-2) removal and may delay the onset of dialysis-related amyloidosis. We assessed the differential effects of high-flux haemodialysis (HD) and on-line haemodiafiltration (HDF) on plasma beta M-2 levels, given the enhanced convective capability of HDF. Methods: We measured pre-dialysis 2 M levels in 297 patients in a programme employing both high- flux HD and HDF, then analysed the relationship of beta M-2 to modality and other variables. Results: Independent determinants of plasma beta M-2 levels were residual renal function, age, HD vintage, and C-reactive protein load, but not the patient's predominant modality (high-flux HD or HDF). Patients with KRU levels < 0.5 ml/min had significantly higher beta M-2 levels than patients with KRU between 0.5 and 1 ml/min. Conclusions: Residual renal function is of overriding importance as a determinant of beta M-2 levels in HD patients and may supersede enhanced convective clearance by HDF. Beneficial effects extend to very low levels of residual renal function. Copyright (c) 2007 S. Karger AG, Basel.