Comparative Analysis of Commercial Immunoassays for the Determination of Total, Intact, and Nonintact Luteinizing Hormone in Urine

ABSTRACT Background In our recent publications, we reported the identification of three different molecular forms of total luteinizing hormone (LH) in urine, the intact LH, the free beta‐subunit (LHβ), and its core fragment of LHβ (LHβcf), the latter two establishing the nonintact portion of LH. Following the discontinuation of the Delfia immunofluorometric assay (IFMA) (Wallac, PerkinElmer Finland, Finland), a leading method for detecting urinary LH for 30 years, this study seeks to assess the efficacy of three alternative commercial immunoassays in identifying various forms of U‐LH. Methods Diluted urine samples underwent gel filtration to separate them into fractions, each containing different forms of LH. These were then assayed using Delfia IFMA, Architect LH (Abbott, USA), Elecsys LH Cobas (Roche, Switzerland), and Immulite 2000 LH (Siemens, Germany) immunoassays. Results Both Delfia and Immulite assays detected total U‐LH, that is, all three forms of U‐LH, including intact LH, LHβ, and LHβcf. Cobas detected only intact LH and LHβ, whereas Architect detected solely the intact LH. Conclusions Immulite assay can be an alternative tool to detect all forms of urinary LH, a feature likely to be instrumental in developing noninvasive, practical, and scalable solutions for evaluating total U‐LH changes during minipuberty in neonates, during the onset of central puberty in peripubertal children, puberty‐associated disorders in adolescents, and the fertility window in women, with a special focus on postpeak changes.