RESUMEN
OBJECTIVES: Biotin causes negative interference with thyroglobulin measurement using the Access thyroglobulin assay. Recently, Beckman reformulated the thyroglobulin assay to overcome biotin interference. We investigated the effect of biotin on both current and newly formulated assays. METHODS: Four serum pools were prepared using specimens containing various amounts of thyroglobulin. Then aliquots of each pool were supplemented with various amounts of biotin, and thyroglobulin concentrations were measured by both the current and the new assays. In addition, 3 volunteers ingested 10 mg biotin, and specimens were drawn before and 2 hours after taking biotin. Thyroglobulin concentrations before and 2 hours after taking biotin were measured by both assays. RESULTS: In the presence of biotin, thyroglobulin concentrations were reduced significantly using the current assay, but no significant change was observed using the newly formulated assay. We observed similar results in vivo. CONCLUSIONS: The newly formulated thyroglobulin assay by Beckman is free from biotin interference.