EVALUATION OF THE ABBOTT IMX ESTRADIOL ASSAY

The performance characteristics of a microparticle capture enzyme immu noassay (Abbott IMx) for the measurement of 17beta-estradiol in serum were evaluated in reference material and for use in an in vitro fertil ization/embryo transfer (IVF/ET) program. Sample volume is 150 mul; dy namic range: 0 to 11 nmol/L [0-3000 pg/mL]. In our laboratory, the IMx Estradiol assay showed a within-run and between-run precision of 5-8% . The estimated low end of the practical working range was 0. 10 nmol/ L [28 pg/mL]. The mean recovery on 2- to 32-fold dilutions of patient samples-with estradiol concentration of 5.3-8.8 nmol/L [1450-2400 pg/m L] was 101%. Samples with IMx estradiol concentration ranging from 0.1 0 to 18 nmol/L [28-4860 pg/mL] exhibited good correlation with Clinica l Assays(TM)-Estradiol (r = 0.995). A linear regression analysis indic ated that the Abbott IMx Estradiol yielded approx. 37% higher results than the Clinical Assays(TM)-Estradiol. The clinical relevance of the differences is, however, minimal. The new IMx assay can reliably be us ed to determine estradiol in sera from women enrolled in an. IVF/ET pr ogram, for E2 Measurement during the normal menstrual cycle and in ser a from men, but IMx Estradiol ought to be used critically at the menop ause. The IMx assay offers some advantages over the radioimmunoassay: it is safer to use, the enzyme-labelled antigen is stable for several months, the assay allows for a minimum calibration curve storage of tw o weeks, and the IMx system offers the advantages of significant time and labor reduction. In conclusion, the method is an attractive altern ative to RIA.