Ultrapure Dialysate Reduces Dose of Recombinant Human Erythropoietin

Dear Sir, The widespread availability of recombi-nant human erythropoietin (rHU-EPO) is one of the greatest advances in clinical neph-rology. Approximately 90–95% of dialysis patients treated with rHu-EPO respond with an improvement in their anemia, but individual doses may vary considerably. The most important factors causing this variation are acute or chronic inflammatory processes which may lead to marked resistance to rHu-EPO. It is a well-known fact that exposure of patient's blood to even mildly contaminated dialysate contributes to the systemic inflammatory syndrome of uremia by induction of cytokine synthesis [1]. However , there are no data indicating whether differences in the microbiological quality of the dialysate may affect the response to rHu-EPO in patients receiving regular hemodial-ysis. The aim of our prospective cross-over investigation was to compare the effect of potentially contaminated, commercial (un-filtered) and online produced, ultrapure dial-ysate on rHu-EPO doses. Twenty-four stable anuric dialysis patients gave informed consent to participate in the study which was approved by the local ethics committee. They all had normocytic normo-chromic anemia of end-stage renal disease and normal levels of folic acid, vitamin B 12 and ferritin. None of the patients had acute or chronic infection, inflammatory disease, malignancy or chronic bleeding disorders or used immunosuppressive drugs or angioten-sin-converting enzyme inhibitors. Hemodi-alysis was performed with volumetrically controlled ultrafiltration (MTS 4008, Frese-nius, Bad Homburg, Germany) and biocom-patible high-flux dialyzers (Polysulfone, F60 Fresenius, Bad Homburg, Germany). The bicarbonate dialysate was either commercial or ultrafiltrated using polysulfone filters. Each treatment session lasted 3–5 h, with blood flow rates between 250 and 350 ml/ min, and dialysate flow rates at 500 ml/min. Twelve patients each were randomly assigned to treatment with unfiltered (commercial) dialysate for 3 months and crossed over to ultrafiltrated dialysate for another 3 months or were treated in the reverse order. The microbiological quality of the dialysate was checked monthly. Plasma C-reactive protein (CRP) levels and circulating inter-leukin-6 concentrations were measured by highly sensitive enzyme-linked immunosor-bent assays. There were no statistically significant differences in the demographic characteristics or treatment-associated parameters between the 2 study groups at recruitment. Both groups had comparable target hemoglobin concentrations and rHu-EPO doses (ß-epoie-tin, Boehringer, Mannheim, Germany) at the start of the study (table 1). In group I continuation of commercial unfiltered dialysate (median 140, range 60– 400 CFU) did not result in a significant change of hemoglobin levels (10.2 B 0.2 g/ dl), rHu-Epo doses (90 B 50 U/kg/week) …