Antithyroid medications not only reduce TH via inhibition of the effects of thyroid peroxidase, but they also exert an immunosuppressive effect via reduction in the number of circulating activated T helper/inducer cells and increment in the number of circulating activated T suppressor/cytotoxic, leading to inhibition of the initiation and progression of thyroid carcinoma [8]. This evidence concerns the gene TPO and thyroid gland carcinoma.