GD is the predominant AITD and is caused by autoantibodies to thyroid-stimulating hormone receptor (TSHR) augmenting its action and inducing thyrotoxicosis; however, two other autoantibodies, directed to thyroid peroxidase (TPO) and thyroglobulin (Tg), may also occur and share classical marker of HT (Fountoulakis and Tsatsoulis 2004). This evidence concerns the gene TPO and hematocrit.