Coagulation and fibrinolysis in thyroid dysfunction.

Various abnormalities of hemostasis, ranging from subclinical laboratory abnormalities to clinically significant disorders of hemostasis, and rarely major hemorrhage or thromboembolism, may occur in patients with thyroid diseases. The objective of this review is to discuss the relationships between thyroid dysfunction and hemostasis (primary hemostasis and coagulation/fibrinolytic system). According to the recent literature, most of the hemostatic abnormalities associated with thyroid dysfunction are the consequences of direct effects of thyroid hormones on the synthesis of various hemostatic parameters. Thyroid autoimmunity may also modify the processes of primary and secondary hemostasis. We have concluded that hyperthyroidism is generally associated with hypercoagulability and hypofibrinolysis, whereas the hemostatic profile in hypothyroidism depends on the severity of the disease. As few data are available on hemostasis in subclinical thyroid disease, further studies on this subject are needed.