There are several other causes for primary hypothyroidism and they can be listed as antithyroid medications (propylthiuracil), thyroid gland tumors, biosynthetic defects in iodine organification, iodine deficiency or excess (Wolff-Chaikoff effect) and some medications such as amiodarone (contains iodine), lithium, tyrosine kinase inhibitors and cytokines (interferon-γ and interleukin-2) [3, 6]. This evidence concerns the gene IL2 and thyroid tumor.