Immunoassay of gonadotropins using a fully-automated benchtop analyser

We assessed the analytical performance of the Abbott IMxTM immunoassay analyser for total beta human chorionic gonadotropin (Beta hCG), follicle-stimulating hormone (FSH) and luteinising hormone (LH). The within-run CVs for various analyte concentrations were 2% to 6% while those for between-run imprecision in routine assay ranged from 4% to 10%. IMxTM values correlated well with radioimmunoassay for beta hCG, and immunoradiometric assay for FSH and LH; the correlation coefficients (r) were 0.97, 0.99 and 0.98 for total beta hCG, FSH and LH respectively. The average sensitivities were approximately 3.1, 0.2 and 0.5 iu/l for beta hCG, FSH and LH, respectively. Sample carry-over was not detected and there was negligible cross-reaction between LH and beta hCG in the respective assays. The automatic sample dilution protocol for beta hCG was superior to the manual procedure. The IMxTM is easy to operate and is able to process 24 samples in 40-45 minutes.