Coagulation and fibrinolysis in thyroid disease.

The levels of components of the coagulation mechanism and fibrinolytic system in 20 hyperthyroid patients and 9 hypothyroid patients were compared with those of 20 euthyroid control subjects. The mean levels of fibrinolytic activity and plasminogen were significantly reduced in the hyperthyroid patients while mean levels of alpha1-antitrypsin and C1 inactivator were increased. Patients with hypothyroidism had significantly increased levels of fibrinolytic activity and alpha2-macroglobulin, a prolonged partial thromboplastin time, and reduced levels of factor XII and antithrombin III.