SERPINC1 and autoimmune thyroid disease: Moderate hypothyroidism, subclinical hypothyroidism, and autoimmune thyroid diseases, on the other hand, would appear to be more frequently associated with a prothrombotic state, due to increased fibrinogen, FVIII, and PAI-1 levels, increased mean platelet volume, decreased antithrombin-III, and a global decrease in fibrinolytic activity [64,69,70,71,72,73].