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Epoetin (recombinant human erythropoietin) is now a widely available though expensive treatment for the anaemia of chronic renal failure, and is effective in more than 95% of patients. Complications of epoetin in this context include hypertension in a third of cases, including hypertensive encephalopathy in a few, and thrombosis of shunts or vascular access devices. Fears that epoetin would cause progression of renal failure have not generally been confirmed, but hyperkalaemia may be a problem in the initial phase of treatment. Epoetin is up to twice as effective when administered subcutaneously rather than intravenously. Responding patients will normally do so within 3 months of starting epoetin. Failures to respond are usually due to iron deficiency or intercurrent disease. Other diseases associated with anaemia and an inappropriately low serum epoetin level include prematurity, the anaemia of cancer and rheumatoid arthritis. The baseline serum endogenous erythropoietin may provide a guide to response in some of these cases. Some encouraging results are being published. Situations where the serum erythropoietin levels are normal or elevated where epoetin has been employed include boosting of haematocrit presurgery as an adjunct to autologous blood donation, treatment of anaemic patients with myelodysplastic syndromes, and improvement of athletic performances.

The oxidative injury to erythrocytes, red blood cell (RBC) rigidity and splenic hemolysis was assayed in 17 chronically hemodialyzed patients before and during recombinant erythropoietin (EPO) treatment. When a stable hematocrit between 30 and 35% had been established for at least 4 months, a statistically significant increase in RBC volume, hemoglobin concentration, hematocrit, reticulocyte count, and several RBC enzymes (2,3-diphosphoglycerate, glucose 6-phosphate dehydrogenase, pyruvate kinase, hexokinase) was noted. This indicated significant RBC rejuvenation under the influence of EPO. However, no significant improvement in the RBC oxidative sensitivity, RBC deformability, splenic RBC volume, slow mixing splenic RBC volume, and the intrasplenic RBC transit time could be disclosed. These data confirm the existence of an extra-erythrocytic factor in uremic plasma, which is partly responsible for a reduced RBC life span in hemodialysis patients despite EPO treatment.

The clinical and ferrokinetic effects of escalating doses of subcutaneously administered recombinant human erythropoietin (rh-EPO) were studied in ten patients with myelodysplastic syndromes and severe transfusion-dependent anemia. Red blood cell transfusion requirements diminished in four patients, and one of the patients eventually became transfusion independent with an EPO-induced rise of Hb from 7.7 g/dl to 12.3 g/dl. Endogenous serum levels of EPO were significantly increased in all patients (100-5700 mU/ml), but three of four responders had a relatively low baseline level. The effective red cell iron turnover (RCIT) improved in two responding patients and even normalized in one patient. This increase in RCIT was accompanied with a decline in the ineffective red cell iron turnover (IIT). The other responding patients had a relatively preserved RCIT before EPO treatment. EPO therapy further increased the fraction of IIT in the latter patients. Red cell survival time did not increase during EPO therapy, even in the responding patients. One transient and one maintained increase in platelet count were observed. Disease progression with a sustained increase in blast cells in one patient and a transient elevation of blasts in another patient was seen. No other side effects of EPO therapy were observed. These results suggest that anemic MDS patients with low serum EPO levels and relatively spared effective erythropoiesis as measured by ferrokinetic studies may be the best candidates for treatment with recombinant human EPO.