Objective: We determined the profile of coagulation/fibrinolytic and vascular endothelial cell function parameters including plasminogen activator inhibitor (PAI) and thrombin-activatable fibrinolysis inhibitor (TAFI), tissue factor pathway inhibitor (TFPI), thrombomodulin (TM), and tissue plasminogen activator (tPA) levels in children with hypothyroidism. The gene discussed is THBD; the disease is hypothyroidism.