The Role of Hematocrit in Efficiency of Dialysis

Abstract

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 (K_d) and Kt/V were plotted against Hct. Hct showed a significant inverse correlation with K_d(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 ≧ 37%. In the patients treated with rHuEPO, Hct rose from 18 ± 1 to 35 ± 5% (p < 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.

Should the Hematocrit Be Normalized in Dialysis and in Pre-ESRD Patients?

“…This phenomenon was first recognized in the initial epoetin study by Eschbach et al [6] in which several patients were found to develop profound hyperkalemia. More recently, Movilli et al [22] found an inverse relationship between hematocrit and both dialyzer clearance (p = 0.003) and Kt/V (p = 0.0002); the lowest Kt/V values were in the group with a hematocrit 637%. This has also recently been the subject of a study by Ronco et al [23] in which it was shown that dialyzer efficiency was reduced in hemodialysis patients following normalization of hemoglobin with epoetin.…”

Influence of Erythropoietin Treatment on Dialyzer Reuse

“…15]. However, short HD regimens [15] and high Hb levels [16,17] are reported to be the culprits for worsening UKM during r-HuEPO treatment. Reduction in dialyzer performances in such conditions may be caused by several factors: an increase in red blood cell mass transfer rate within the dialyz er [18], a reduction in blood velocity within Influence of Erythropoietin Treatment on Dialyzer Reuse the arteriovenous fistula and dialyzer due to the higher Hct [2], an increased blood viscosi ty in patients with high Hct may be associated with a change in the boundary layer at the interface between the blood and the dialyzer membrane, which could reduce urea transfer [6.…”

Effect of High Haematocrit on the Efficiency of High-Flux Dialysis Therapies

“…New concepts of adequacy also focus on the removal of larger molecules such as β 2 -microglobulin (β 2 M) that diffuse less freely. While changes in Hct are not thought to be of major significance in the clearance of low molecular weight substances during dialysis [2,3,4], the impact on higher molecular weight substances has not been extensively investigated.…”