EVALUATION OF AN IMMUNOENZYMOMETRIC ASSAY (IEMA) USING AUTOMATED-SYSTEM FOR DETERMINATION OF LUTEINIZING-HORMONE AND FOLLICLE-STIMULATING-HORMONE

It has been proposed that automated systems for immunoenzymometric ass ay (IEMA) may substitute traditional radioimmunoassay (RIA) for measur ement of luteinizing hormone (LH) and follicle-stimulating hormone (FS H) in blood due to the advantage of being more rapid, higher sensitivi ty, lower cost and not requiring radioactive reagents. The study was d esigned to evaluate both systems using serum samples to determine lute inizing hormone (LH) and follicle-stimulating hormone (FSH) concentrat ions. The automatic system (ES-300) for IEMA utilized two monoclonal a ntibodies, 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 vari ous clinical problems (''problem group'') as well as blood samples fro m patients in whom FSH and LH concentrations were already known (''hig h'', ''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 RTA was 1.95 mIU/ml for both hormones. Intra - and interassay coefficient of variation were below 10% within the ra nge of 15 - 150 mIU/ml for FSH and 5 - 100 mIU/ml for LH; however, the coefficient of variation was 15 - 25% at lower concentrations of FSH and LH. Accuracy of IEMA was evaluated by recovery percentage, thus wh en high and medium concentrations of FSH and LH were analyzed the reco very was between 99 - 104%. On the other hand, the recovery was 110% w hen low levels of FSH and LH were used. In conclusion, IEMA resulted r eliable when FSH and LH concentrations are in the middle and high rang e; likewise, the detection limit of IEMA was lower than RIA, particula rly for FSH. On the bases of these results,IEMA showed several advanta ges over RIA, but its reliability diminishes when serum samples contai n low FSH and LH concentrations. It is important to extend these studi es to steroid assays and elaborate a database in each laboratory.