THE REQUIRED DOSE OF ERYTHROPOIETIN DURING RENAL ANEMIA TREATMENT IS RELATED TO THE DEGREE OF IMPAIRMENT IN ERYTHROCYTE DEFORMABILITY

Background. Renal anaemia is rapidly corrected by recombinant human er ythropoietin (rHuEpo) therapy, but the dose required varies greatly. S ince impaired erythrocyte deformability may be one factor contributing to the development of renal anaemia, the interrelationship between th at variable and the rHuEpo requirement was examined. Methods. Twenty-f ive patients treated with hemodialysis and rHuEpo for at least 6 month s were included in the study. The Hb value had been stable and the rHu Epo dose unchanged the last two months. Using a rotational viscometer, the fluidity of erythrocytes, separated from plasma and re-suspended in isotonic buffered saline to a standardized haematocrit, was taken a s a measure of erythrocyte deformability. Results. The average weekly dose of s.c. epoetin alpha was 186 +/- 93 U/kg body weight (range 56-3 70). The dose was correlated to the reticulocyte fraction (R = 0.69, P = 0.0001). When the rHuEpo dose was used as dependent variable and bl ood haemoglobin concentration, serum (S) albumin, S ferritin, S alumin ium, S PTH, S urea, Kt/V/week, erythrocyte fluidity, and plasma viscos ity were used as independent variables in a stepwise multiple regressi on analysis, only erythrocyte fluidity remained significantly negative ly correlated to the rHuEpo dose (R = 0.5, P = 0.01). Despite a tenden cy towards higher doses of rHuEpo in patients with a C-reactive protei n concentration exceeding 20 mg/l, the Hb was lower in these patients. Conclusions. We conclude that the interindividual differences in bone marrow response to rHuEpo were small in these patients; Impaired eryt hrocyte deformability and inflammation seem to be factors associated w ith increased rHuEpo requirement.