Differential effects of progestins on hemostasis

Area of Science:

• Reproductive endocrinology and hemostasis

Background:

• Large studies suggest progestin use in hormone replacement therapy (HRT) may interfere with hemostasis, potentially increasing venous thrombotic events.
• The impact of progestins on hemostasis is complex and may depend on various factors including type, dose, route, duration, and co-administered estrogens.

Purpose of the Study:

• To evaluate available publications on whether progestins interfere with hemostasis.
• To determine if interference varies when progestins are given alone or in combination with estrogens.

Main Methods:

• Systematic review and evaluation of existing publications on progestin and hemostasis.
• Analysis of progestin effects based on administration route (oral/parenteral), combination with different estrogens, and treatment duration.

Main Results:

• Natural progesterone showed no negative effects on hemostasis via oral or parenteral routes.
• Progestin-only pills (POP) and parenteral progestins did not demonstrate adverse effects on hemostasis.
• Estrogen/progestin combinations showed increased venous thromboembolism risk, attributed to the estrogen component, with some oral contraceptives showing higher risks with specific progestins (desogestrel, gestodene) compared to levonorgestrel.
• In HRT, decreased antithrombin factors may explain increased venous thrombotic events.

Conclusions:

• Progestins exhibit diverse effects on the hemostatic system, influenced by their distinct biological activity patterns.
• Some progestins can negatively impact vascular function, affecting estrogen's vasodilating action and promoting vascular changes, while others do not.