Moreover, serum TGF-β concentrations are reduced between the first transitory hyperthyroid phase (during which this growth factor is intrathyroidal produced and subsequently activated, stimulating thus thyroid follicular cell destruction, and increasing in an autocrine manner its own synthesis) and the second (associated with hypothyroidism) phase of post-partum thyroiditis [55]. This evidence concerns the gene TGFB1 and thyroiditis.