Li D, et al. - The objective of this study was to evaluate the performance of particular biotinylated immunoassays after 1 week of ingesting 10 mg/d of biotin, a dose common in over-the-counter supplements for healthy adults. In this preliminary study of 6 healthy adult participants and 11 hormone and nonhormone analytes measured by 37 immunoassays, ingesting 10 mg/d of biotin for 1 week was related to potentially clinically imperative assay interference in some but not all biotinylated assays studied. These outcomes ought to be considered for patients taking biotin supplements before ordering blood tests or when interpreting results.