Abstract
A new radioimmunoassay system for erythropoietin (EPO) titers in plasma or serum was established using recombinant human EPO which was raised recently. It has excellent specificity, sensitivity and reproducibility, and can be used for clinical purposes. EPO titers could be directly measured within the range of 3-250mU/ml and the sensitivity was 5mU/ml.
EPO titers were 16.1±8.6mU/ml (m±SD) in 428 patients on maintenance dialysis and 17.1±7.2mU/ml in 86 normal controls. No significant difference was observed between the two groups. EPO titers in the dialysis patients were extremely low compared with their low hematocrit, and no correlation was observed between EPO and hematocrit. EPO titers were similar in patients who had received large blood transfusions and in patients not tranfused, although frequent blood transfusions were required in some patients with severe anemia whose EPO titers were lower. EPO titers tended to increase with age in both groups, though they decreased slightly above 70 years of age in normal controls. No correlation was observed between EPO and the duration of dialysis, though the number of patients with higher hematocrit tended to increase with the duration of dialysis. Among the various etiologies of renal failure, the highest EPO titer was observed in patients with multiple myeloma. Anemia was mild and EPO titer was slightly higher in patients with polycystic kidneys. EPO titers were similar in patients with and without the administration of anabolic steroids or iron preparations. There was no correlation between EPO and reticulocyte count, serum concentration of urea, creatinine, iron or ferritin.
