Clinical validation of an RIA for natural and recombinant erythropoietin in serum and plasma.

A sensitive radioimmunoassay (RIA) for the detection of erythropoietin (EPO) was developed using antibody directed against EPO from human urine. With 100 microL of sample, the assay is sensitive to 7 U/L, well below the mean EPO level in normal males (15.1 +/- 3.5 U/L) or females (15.4 +/- 4.8 U/L). Dilutions of a variety of human serum samples show a parallel relationship with the standard EPO. Clinical validation of the RIA was confirmed by appropriate increases or decreases of EPO levels in various types of anemia and polycythemia. Serum EPO levels were also measured in volunteers participating in an autologous blood donation study. The RIA proved to be quite sensitive, detecting small increases even after a single unit phlebotomy. This RIA of human EPO meets all the requirements of a routine clinical assay in terms of specificity and clinical sensitivity and can be easily conducted in routine clinical laboratories.