Thrombin-activatable fibrinolysis inhibitor in hyperthyroidism and hypothyroidism

Introduction: Endocrine disorders affect both the coagulation and fibrinolytic systems, and have been associated with the development of cardiovascular diseases. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a link between the coagulation and fibrinolytic system. The aim of this study was to determine the effect of hyperthyroidism and hypothyroidism on TAFI levels and function. Methods: The effect of hyperthyroidism on TAFI was studied in healthy volunteers who were treated with levothyroxine for 14 days. The effect of hypothyroidism on TAFI was studied in a multicentre observational cohort study. Blood was drawn before treatment of patients with newly diagnosed hypothyroidism and when euthyroidism was achieved. Plasma clot-lysis times, TAFIa-dependent prolongation of clot-lysis and TAFI levels were measured. Results: Hyperthyroidism resulted in a hypofibrinolytic condition and in an enhanced TAFIa-dependent prolongation of clot-lysis. A trend towards decreased plasma TAFI levels was observed in healthy volunteers who used levothyroxine. Hypothyroidism resulted in hyperfibrinolysis and a reduced TAFIa-dependent prolongation of clot-lysis. Discussion: Alterations of TAFIa-dependent prolongation of clot-lysis in patients with thyroid disorders may cause an impaired haemostatic balance. The disturbed haemostatic balance in patients with hyperthyroidism might make them more prone for thrombosis, while the risk for bleeding may increase in patients with hypothyroidism. 142 TAFI in hyperand hypothyroidism