The effect of thyroid hormone on haemostasis and thrombosis

Abstract

In this thesis the relation between thyroid hormones and the coagulation system will be examined. As an introduction, the hypothalamic-pituitary-thyroid axis, the coagulation system and their interactions will be discussed. A short overview of the literature preceding the research reported in this thesis is about the relation between thyroid hormones, the coagulation system, and risk of bleeding and venous thrombosis. In conclusion, in the studies in this thesis we found strong evidence that higher than average levels of FT4 increase the risk of venous thrombosis. Weak evidence is provided that lower than average levels of FT4 give an increased risk of bleeding in patients using vitamin K antagonists. A hypothyroid state possesses probably both pro- and anti-coagulant properties. The effect of FT4 on venous thrombosis is mediated at least by coagulation factors factor VIII and von Willebrand factor.