It has been shown that leptin may play a role in the interaction between thyroid hormones and body composition (24) and leptin could be connected with thyroid autoimmunity (25) and has stimulatory effect on releasing TSH in vivo and has an impact on peripheral iodothyronine deiodinase activity and conversion of T4 to T3 (26). This evidence concerns the gene LEP and autoimmune thyroid disease.