Hormones and thrombosis: the dark side of the moon

Abstract

Background: The main drawback of oral contraceptives (OC) and hormone replacement therapy (HRT) is an increased risk of venous and, to a lesser extent, arterial thrombosis.

Materials and methods: This narrative, case-based review describes the effect of available estrogens and progestogens on the hemostatic system and their potential impact on the risk of thrombosis. Clinical cases are used to illustrate different options for prescribing OC and HRT in the real-word. The aim is to offer discussion topics that could be helpful to guide the choice of different hormonal treatments over a woman's lifetime and in the presence of risk factors.

Results: We describe physio-pathological changes occurring during the administration of hormonal therapies. Furthermore, we analyze the risk of venous and arterial thrombosis associated with different products, routes of administration and additional risk factors. New hormonal preparations, such as estradiol combined with dienogest, as well as non-oral hormonal therapies, are suggested to decrease thrombotic risk significantly.

Discussion: The availability of many products and different routes of administration allow most women to safely use contraception, as well as HRT. We encourage careful counselling instead of inflexible or fearful behavior, as expanding options and choices will allow women to make the best decisions for their health.

Figure 1

Hemostatic changes in women taking the oral contraceptive pill Fbg: fibrinogen; AT: antithrombin; PC: protein C; PS: protein S.

Figure 2

Anti-fibrinolytic activity in women taking the oral contraceptive pill tPA: tissue plasminogen activator.

Figure 3

Relative Risk of venous thromboembolism in women taking third vs second generation oral contraceptive pills RR: relative risk.