QUANTITATIVE ASSESSMENT OF ERYTHROPOIESIS IN HEMODIALYSIS-PATIENTS DEMONSTRATES GRADUAL EXPANSION OF ERYTHROBLASTS DURING CONSTANT TREATMENT WITH RECOMBINANT-HUMAN-ERYTHROPOIETIN

Recombinant human erythropoietin (rHuEpo) has been shown to be effecti ve in correcting the anaemia of chronic renal failure. It has been rep orted that reticulocytes as well as erythroid progenitors increase wit hin 1-2 weeks, with no further elevation beyond this time interval. Ho wever, the erythroblast, poor is quantitatively the most important com partment of erythropoiesis, and the rate, extent and duration of the e xpansion of erythropoietic activity in response to rHuEpo is not known . Treatment with rHuEpo was given to 64 patients i.v. thrice weekly af ter haemodialysis. The effect of rHuEpo was obvious from the early ele vation of reticulocyte counts, but much of this increase was due to a rapid output of shift reticulocytes which levelled off after a few wee ks. Serum transferrin receptor (TfR), a quantitative measure of erythr opoiesis, increased progressively over 6 weeks to reach a plateau phas e at about twice baseline values. The Hct increased progressively and continued to rise steadily after the TfR plateau was reached. The spee d and extent of the expansion of erythropoietic activity correlated wi th the later haematological response to rHuEpo. When rHuEpo was discon tinued, erythropoietic activity returned progressively to baseline val ues, to rise again gradually when treatment was resumed. Part of the H ct increase was also due to haemoconcentration. The results indicate t hat changes in the various erythroid compartments vary considerably in intensity and speed, and that the erythroblast compartment in particu lar is slow to respond to modifications in the erythropoietin stimulus .