ABSTRACT
It has been proposed that automated systems for immunoenxymometric assay (IEMA) may substitute traditional radioimmunoassay (RIA) for measurement of luteinizing hormone (LH) and follicle stimulating hormone (FSH) in blood due to the advantage of being more rapid, higher sensitivity, lower cost and not requiring radioactive reagents. The study was designed to evaluate both systems using serum samples to determine luteinizing hormone (LH) and follicle stimulatin hormone (FSH) concnetrations. The automatic system (ES-300) for IEMA utilized two monoclonal antibodies, one of them on the solid phase was the specific extractant for the antigen, and the other was a peroxidase labeled antibody which recognizes a different epitope in the antigen molecule, specifically bound in linear proportion to the antigen concentration. Blood samples were obtained from patients who were treated at the hospital for various clinical problems ("problem group") as well as blood samples from patients in whom FSH and LH concentrations were already known ("high", "medium" and "low" levels) by previous RIA ("control group"). IEMA showed a higher sensitivity, 0.42 and 0.96 mIU/ml for FSH and LH, respectively, whereas RIA was 1.95 mIU/ml for both hormones. Intra and interassay coefficient of variation were below 10 percent within the range of 15-50 mIU/ml for FSH and 5-100 mIU for LH; however, the coeffcient of variation was 15 - 25 percent at lower concentrations of FSH and LH. Accuracy of IEMA was evaluated by recovery percentage, thus when high and medium concentrations of FSH and LH were analyzed the recovery was between 99 -104 percent. On the other hand, the recovery was 100 percent when low levels of FSH and LH were used. In coclusion, IEMA resulted reliale when FSH and LH concentrations are in the middle and high range; likewise, the detection limit of IEMA was lower than RIA, particularly for FSH. On the bases of these results, IEMA showed several advantages over RIA, but its reliability diminishes when serum samples contain low FSH and LH concentrations. It is important to extend theses studies to steroid assays and elaborate a database in each laboratory