The variable role of erythropoietin deficiency in the pathogenesis of dialysis anaemia.

To evaluate the role of reduced erythropoietin (Ep) production in the pathogenesis of dialysis anaemia, measurements of serum erythropoietin (SEp) concentration by means of a highly sensitive in vitro bioassay were performed in 88 non-nephrectomised non-transfused regular haemodialysis patients. In 50 patients (group 1) SEp levels were lower than 120 mU/ml. In the remaining 38 patients (group 2) SEp concentrations ranged from 120-369 mU/ml. Group 1 showed a highly significant positive correlation between SEp concentration and haematocrit as did 13 anephric patients investigated for comparison. In contrast, group 2 displayed a highly significant negative correlation between SEp concentration and haematocrit. The results demonstrate the existence of two distinctive groups of similar size in regular haemodialysis patients: those with an absolute (group 1) and those with a relative deficiency of Ep (group 2). In the case of the latter, lack of Ep is probably a secondary factor in the pathogenesis of anaemia, whereas uraemic toxicity and blood loss may play a primary role.