The interrelationship between pregnancy, venous thromboembolism, and thyroid disease: a hypothesis-generating review

Abstract

Pregnancy induces physiological changes that affect the risk of thrombosis and thyroid disease. In this hypothesis-generating review, the physiological changes in the coagulation system and in thyroid function during a normal pregnancy are described, and the incidence of venous thromboembolism (VTE) and thyroid disease in and after a pregnancy are compared and discussed. Furthermore, evidence regarding the association between thyroid disease and VTE in non-pregnant individuals is scrutinized. In conclusion, a normal pregnancy entails hormonal changes, which influence the onset of VTE and thyroid disease. Current evidence suggests an association between thyroid disease and VTE in non-pregnant individuals. This review proposes the hypothesis that maternal thyroid disease associates with VTE in pregnant women and call for future research studies on this subject. If an association exists in pregnant women specifically, such findings may have clinical implications regarding strategies for thyroid function testing and potential thromboprophylaxis in selected individuals.

Prolonged APTT and autoimmune overt hypothyroidism identified postpartum: a case report

“…This case illustrates the diagnosis of autoimmune, overt hypothyroidism in a young woman identified postpartum because the biochemical finding of prolonged APTT provided a diagnostic clue to assess her thyroid function. The biochemical findings which suggest a hypocoagulant state in the patient are compatible with previous reports ( 1 , 2 , 3 , 4 ). We specifically observed a prolonged APTT and low levels of coagulation factor VIII and vWF as well as reduced generation of thrombin at the time of diagnosis of severe hypothyroidism.…”

“…Since the patient had no history or ongoing symptoms of bleeding, the biochemical findings were unexpected. Considering the literature on the association between thyroid disease and disorders of the coagulation system ( 4 ), we speculated on any underlying thyroid disease in the patient. She never previously had thyroid function tested, and the decision was made to extend the biochemical evaluation with the measurement of thyroid-stimulating hormone (TSH).…”

“…From some of the earliest observations in the 1960s and later literature reviews, it generally appears that hyperthyroidism and hypothyroidism show opposite associations with the coagulation system. Thus, hyperthyroidism has predominantly been associated with a hypercoagulant state and a higher risk of venous thromboembolic events, whereas hypothyroidism has been associated with a hypocoagulant state and a higher risk of bleeding episodes ( 1 , 2 , 3 , 4 ). Concerning hypothyroidism and the impact of low levels of thyroid hormones, original investigations have mainly described prolonged activated partial thromboplastin time (APTT) along with a decrease in the level of coagulation factor VIII and von Willebrand factor (vWF) ( 5 , 6 ).…”