Comparison between On-Line High-Efficiency Hemodiafiltration and Conventional High-Flux Hemodialysis for Polyclonal Free Light Chain Removal

Background: Polyclonal free light chains (FLC) are considered as middle molecular weight uremic toxins in chronic kidney disease. In this study, we investigate polyclonal FLC removal by comparing conventional high-flux hemodialysis (HD) and online high-efficiency hemodiafiltration (ol-HDF) in end-stage renal disease patients. Methods: We analyzed 31 chronic dialysis patients who were treated by HD then by postdilution ol-HDF during a prospective study. All patients were anuric and without monoclonal gammopathy. Serum pre- and postdialysis FLC were collected during 4 sessions: 1 HD session and 3 ol-HDF sessions. We calculated the reduction ratio using kinetic modeling. Results: The kappa reduction ratio was higher with ol-HDF than with HD (66 +/- 14 vs. 52 +/- 13%, p < 0.001). However, the lambda reduction ratio was not significantly higher with ol-HDF (37 +/- 20 vs. 37 +/- 15%, p = 0.67). Furthermore, predialysis kappa- and lambda-FLC increased with ol-HDF compared with HD (kappa 155 +/- 82 vs. 87 +/- 47 mg/l, p < 0.05; lambda 101 +/- 46 vs. 72 +/- 41 mg/l, p < 0.05). Postdialysis FLC levels were raised only for lambda-FLC with ol-HDF (74 +/- 39 vs. 53 +/- 31 mg/l, p < 0.05) and were not significantly different for kappa. Conclusions: This study shows that lambda-FLC removal is better in ol-HDF compared with HD, whereas there is no difference in kappa-FLC removal. Surprisingly, predialysis kappa and lambda levels are both increased in ol-HDF, which is disturbing since polyclonal excess of lambda-FLC is associated with mortality in chronic kidney disease. (C) 2014 S. Karger AG, Basel