【Abstract】Background Dialysis related amyloidosis (DRA) is a common complication of patients with end stage renal disease. The retention of 2-microglobulin plays an important role in the development of DRA. Different blood purification modalities result in different levels of clearance. Generally speaking, low-flux dialysis(LF-HD) can eliminate little 2-microglobulin during therapy, while hemodiafiltration (HDF) and high-flux dialysis (HF-HD) can clear 2-microglobulin effectively. Objectives To compare the clearance effect of 2-microglobulin between HDF and HF-HD. Methods 12 long-term stable hemodialysis patients were given HDF (post-dilution, with infusion volume 17-25L) and HF-HD respectively in the same day of two weeks. Fresenius-4008 dialysis machines and HF80 high-flux dialyzers were used, while treatment sessions to be compared were carried out in each patient using the same duration, compositions of fresh dialysate, blood flow rate, dialysate/infusate flow rate and anticoagulation protocol. The blood samples were collected just at the beginning, the end of 1st, 2nd, 3rd hour and just before the end of procedure. Meanwhile the waste dialysate samples were collected at the end of 5th, 15th, 30th, 45th, 60th, 90th, 120th, 150th, 180th, 210th, and 235th minute in the same procedure. The total volume of waste dialysate was partially collected from which sample was taken. Radioimmunoassay was used to detect the concentration of 2-microglobulin in blood and dialysate samples. Paired t test was used to compare 2-microglobulin concentration (ug/ml) and total elimination amount (mg). P＜0.05 is considered statistically significant. Result The median age of the patients was 48.5yrs, median years of dialysis was 4yrs. During HDF, average fluid removal amount was 2.47kg. The concentrations of 2-microglobulin (ug/ml) just at the beginning, the end of 1st, 2nd, 3rd hour and just before the end of procedure were (57.6929.61), (31.2020.77), (20.5014.75), (13.9610.02) and (11.298.60) respectively. During HF-HD, average fluid removal amount was 2.28kg. The concentrations of 2-microglobulin (ug/ml) just at the beginning, the end of 1st, 2nd, 3rd hour and just before the end of procedure were (53.2417.65), (32.1224.42), (22.8014.14), (22.4016.54) and (16.009.03) respectively. The results above showed no statistically significant differences between HDF and HF-HD (P＞0.05). In HDF and HF-HD, total elimination amounts of 2-microglobulin (mg) were (413.34246.23) and (230.35134.00) respectively, which showed statistically significant differences. The clearance rate(ml/min) which were (121.0349.80) and (86.1723.33) respectively for HDF and HF-HD also showed statistically significant differences. Conclusion Although at every time-point in the therapies, blood concentrations of 2-microglobulin showed no significant differences between HDF and HF-HD., HDF can eliminate more 2-microglobulin than HF-HD during a single therapy.

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