Ultrapure dialysate and inflammatory response in haemodialysis evaluated by darbepoetin requirements--a randomized study.

BACKGROUND: Dialysate quality has been suggested to influence inflammation status in patients subject to haemodialysis (HD). The aim of this study was to compare ultrapure dialysate (UPD) vs conventional dialysate (CD) with respect to darbepoetin requirements and other inflammation markers. METHODS: A controlled prospective randomized study was carried out on 78 patients from two HD units who were treated with low-flux polyamide dialysers. Patients were assigned to two groups by using different sized blocks per unit and dialysis session. One group received CD treatment while the other was treated with UPD over 12 months. From the groups, 37 patients started treatment with CD and 41 with UPD while 31 patients ended with CD and 30 with UPD. The main variables analysed were haemoglobin (Hb) and darbepoetin dose; other variables studied were C-reactive protein (CRP), albumin, interleukin-6 (IL-6) and interleukin-1 receptor antagonist (IL-1Ra). RESULTS: No significant differences were observed between the two groups for the variables analysed. At the beginning of the study the following values of CD and UPD were assessed: Hb 11.3 and 11.3 (g/dl); darbepoetin dose: 0.49 and 0.44 (microg/kg/week); CRP: 13 and 24 (mg/l); albumin: 3.8 and 3.7 (g/dl); IL-6: 5.94 and 4.18; and IL-1Ra: 345 and 420 (ng/l), respectively. At the end of the study the values of CD and UPD were: Hb 12 and 11.9 (g/dl); darbepoetin dose: 0.47 and 0.48 (microg/kg/week); CRP: 14 and 14 (mg/l); albumin: 3.8 and 3.7 (g/dl); IL-6: 14.03 and 12.93 and IL-1Ra: 322 and 340 (ng/l). CONCLUSIONS: UPD does not improve the inflammatory status evaluated by darbepoetin requirements in conventional HD patients treated with low-flux polyamide dialyser. Further controlled studies are required to evaluate the clinical influence of UPD in HD with other low- and high-flux membranes.