Fibrinogen and fibrinolytic activity in hyperthyroidism before and after antithyroid treatment.

Plasma concentration of fibrinogen and B beta 15-42, a specific product of fibrinogen metabolism induced by plasmin, were measured in a group of patients with untreated hyperthyroidism and in controls. Significantly increased plasma levels of both parameters were observed in hyperthyroid patients. The restoration of euthyroidism either by antithyroid drug or by radioiodine caused a significant decrease of fibrinogen and B beta 15-42. These data indicate that hyperthyroidism is another clinical condition associated with increased concentration of fibrinogen and B beta 15-42.