INFLUENCE OF HUMAN ANTI-MOUSE ANTIBODIES ON THYROTROPIN IN-VITRO ANALYSIS - A COMPARISON OF 6 THYROTROPIN IRMA KITS

Objective. The aim of the study was to evaluate the influence of human anti-mouse antibodies on the measurement of thyrotropin. Investigatio ns: Samples from 11 patients with measureable human anti-mouse antibod y titres (19 mu g/l-3880 mu g/l) after radioimmuno-scintigraphy were a nalysed with 6 different thyrotropin immuno-radiometric assay kits (IR MA). Each sample was analysed in the routine way (sample influenced by human anti-mouse antibodies), as well as after incubation with murine immunoglobulin to precipitate human anti-mouse antibodies (samples no t influenced by human anti-mouse antibodies). Results: Two kits showed clear deviations of measured thyrotropin levels when the human anti-m ouse antibody titres were higher than 1350 mu g/l. A third kit was inf luenced to a lesser extent by human anti-mouse antibodies. Three of th e 6 investigated thyrotropin IRMA kits produced thyrotropin values tha t were unaffected by the presence of elevated human anti-mouse antibod ies. In comparison with former studies after immunotherapy, the thyrot ropin deviations were marginal. However, differences were found betwee n the commercially available thyrotropin assays. According to the resu lts of this study only three out of the six investigated kits were una ffected by human antimouse antibodies. Conclusion: Since thyrotropin i s one of the key quantities for the endocrinologist dealing with the t hyroid gland, every laboratory should ensure high quality thyrotropin assays by critically analysing their method for human antimouse antibo dy.