On‐line haemodiafiltration. Remarkable removal of β2‐microglobulin. Long‐term clinical observations

Background. The accumulation of β2‐microglobulin (β2‐M) in long‐term dialysis patients may lead to dialysis amyloidosis. In this respect, the removal with different modes of on‐line haemodiafiltration (HDF) of β2‐M was studied. Long‐term clinical observations in patients with more than 10 years of dialysis, treated mainly with biocompatible and highly permeable membranes and in the last years with on‐line HDF are also reported. Methods. In the first part of this report, the reduction ratios and clearances of β2‐M, blood urea nitrogen, creatinine and phosphorus (P) of on‐line HDF with 40 to 120 mI/min replacement fluid are compared with bicarbonate haemodialysis (HD). In the second part, we investigated 16 patients with more than 10 years of dialysis treatment. The prevalence of dialysis amyloidosis and the mean values for serum albumin, serum total cholesterol, HDL and LDL cholesterol and parathyroid hormone are reported, as well as the mean dose of erythropoietin. Results. In the first part with on‐line HDF, starting from HDF 60 ml/min a significantly higher β2‐M reduction ratio and clearance vs HD is noted. In HDF100 (i.e. with 24 l replacement volume per 4‐h treatment) vs HD, a β2‐M reduction ratio of 72.7% vs 49.7% (P=0.0000) and a β2‐M clearance of 116.8 vs 63.8 ml/min (P=0.0000) was obtained. Comparing HDFl20 with HDF100, there is a significantly higher β2‐M clearance with the former (P