ABSTRACT
This chapter discusses the delicate balance of anabolic enzymes for thyroid hormone (TH) biosynthesis, peroxides, and the detoxifying glutathione peroxidase (GPx). The thyroid gland is an exceptional tissue specialized in accumulating the trace element iodide and using it for the biosynthesis of THs. The essential oxidation of iodide in the follicular lumen results from the interplay of a number of specialized thyroid enzymes and their concerted interaction in the generation, safe metabolism, and control of hydrogen peroxide and thyroglobulin (TG). The biosynthesis of TH depends on the thyroid-specific large globular protein TG that is secreted into the follicular lumen as the scaffold for TH biosynthesis. There is evidence that TG also acts as a feedback regulatory signal for TH biosynthesis, affecting dual oxidases expression, hydrogen peroxide tone, and follicle activities. Besides the GPx, other selenoprotein gene variants have been reported to modifying Hashimoto's thyroiditis risk, e.g., polymorphisms in the SELENOS gene.
