Background: Automated immunoassays utilizing the interaction between streptavidin and biotin are widely used. Nonetheless, biotin remains an often overlooked confounder.
Methods: We report the case of a 54-year-old female patient with progressive multiple sclerosis and Hashimoto's thyroiditis who presented herself for a follow-up. Measurements on Roche's cobas® 8000 modular analyzer series suggested severe hyperthyroidism. Initially, no relevant confounders could be identified.
Results: All requested thyroid parameters were measured with alternative methods, yielding plausible results.
Conclusions: Biotin is a significant confounder in many immunoassays. Alternative measurement methods or methods of biotin neutralization need to be implemented for certain situations.