Endogenous erythropoietin in patients on regular dialysis therapy

In a group of 66 patients with chronic renal failure having regular dialyzation treatment the serum concentration of endogenous erythropoietin (EPO), haemoglobin levels (Hb), haematocrit (Ht) and serum creatinine (Cr) were assessed. The examined subjects were never treated with recombinant erythropoietin and deficiency of iron, folic acid and vitamin B12 was ruled out. Endogenous EPO was assessed by the authors own RIA method, normal values being 24-42 mU/ml. The mean EPO concentration in the whole group of patients was 37.4 +/- 15.3 mU/ml, whereby 12 patients had an EPO serum concentration higher than the upper range of normal values. Between EPO concentrations and Hb values a certain positive correlation was found (r = 0.42). A similar relationship was revealed also between EPO concentrations and Ht values (r = 0.41). Patients with EPO values higher than 42 mU/ml had, as compared with the other patients, significantly higher values of erythrocytes (p .001). Statistical analysis did not reveal any relationship between EPO and Cr concentrations (r = -0.04). A low negative correlation was found between Cr and Hb values (r = -0.31) and between Cr and Ht values (r = -0.25). In the discussion the authors analyze the contemporary state of the problem of anaemia in chronic renal failure. Based on hitherto assembled knowledge they formulated the hypothesis ascribing considerable pathogenetic importance in the development of anemia to reduced sensitivity of bone marrow to EPO, probably as a result of retention of uraemic toxins and inhibitors of erythropoiesis. Inadequate EPO formation could be only a factor which makes it impossible for the developing anaemia to compensate and is due to an animpaired feedback at the level of recognition of the hypoxic signal.