The role of hematocrit in efficiency of dialysis.

To test the role of hematocrit (Hct), particularly when in the nearly normal range, on efficiency of dialysis, we analyzed the urea kinetics for 36 metabolically and hematologically stable patients on regular dialysis treatment and for 7 patients from this group before and after 3 months of treatment with human recombinant erythropoietin (rHuEPO). The volume of distribution of urea (V), the dialyzer clearance (Kd) and Kt/V were plotted against Hct. Hct showed a significant inverse correlation with Kd (r = 0.479, p = 0.003) and Kt/V (r = 0.572, p = 0.0002). Further division of the patients into groups with respect to Hct showed that the lowest Kt/V values were in the group with Hct greater than or equal to 37%. In the patients treated with rHuEPO, Hct rose from 18 +/- 1 to 35 +/- 5% (p less than 0.0001), and Kt/V decreased from 1.22 +/- 0.21 to 1.09 +/- 0.18 (p = 0.037). We conclude that Hct exerts a negative influence on efficiency of dialysis as evaluated by Kt/V. This is important for patients with normal or nearly normal Hct levels as well as for patients treated with rHuEPO, for whom normalization of Hct is pursued.