We know that the core of the autoimmune process in HT is a breakdown in self-tolerance to thyroid autoantigens, which leads to thyroid destruction by infiltration of CD4+ T cells, macrophages, and plasma cells, which produce auto-antibodies against thyroid peroxidase (anti-TPO) and thyroglobulin (anti-Tg) [57]. This evidence concerns the gene TPO and hematocrit.