Toxic goiter occurs in three forms, namely, Graves' disease, toxic adenoma, and toxic nodular goiter, which result mainly from a hypersensitivity reaction to an autoantibody IgG that acts on surface receptors for TSH of thyroid epithelium and which are associated with high levels of thyroid hormones and with a decreased release of TSH (Chardes et al. 2002). This evidence concerns the gene TG and toxic multinodular goitre.