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Plasma levels of activated factor VII decrease during the menstrual cycle
S Kapiotis1, B Jilma, T Pernerstorfer
1Department of Clinical Pharmacology-TARGET, General Hospital Vienna, University of Vienna, Austria. stylianos.kapiotis@univie.ac.at
Insights
Men exhibit higher activated factor VII (FVIIa) levels than women, with FVIIa fluctuating during the menstrual cycle. Female hormones may down-regulate FVIIa, potentially explaining gender differences in cardiovascular risk.
Area of Science:
- Cardiovascular Science
- Hematology
- Endocrinology
Background:
- Men possess a higher cardiovascular risk than women, often attributed to the cardioprotective influence of female sex hormones.
- This gender disparity may be linked to differences in the activation status of the coagulation system.
Purpose of the Study:
- To compare plasma levels of activated factor VII (FVIIa) between men and women.
- To investigate the impact of the menstrual cycle on FVIIa levels in women.
Main Methods:
- A prospective study involving 20 healthy men and 20 healthy young women.
- Measurement of plasma FVIIa and prothrombin fragment (F1 + 2) levels across different menstrual cycle phases.
Main Results:
- Men consistently showed significantly higher FVIIa levels (60 mU/ml) compared to women throughout all menstrual cycle phases.
- In women, FVIIa levels were highest during the follicular phase (41 mU/ml) and decreased during midcycle (34 mU/ml) and the luteal phase (33 mU/ml).
- Prothrombin fragment (F1 + 2) levels decreased significantly during the midcycle and luteal phases in women.
Conclusions:
- Plasma FVIIa levels are higher in men than in women.
- Endogenous female sex hormones appear to down-regulate FVIIa during the menstrual cycle.
- These hormonal influences on FVIIa may contribute to the observed gender differences in cardiovascular risk.
Abstract:
Men have an increased cardiovascular risk as compared to women, which is largely ascribed to the cardioprotective effects of female sex steroids. We hypothesised that this may be reflected by differences in the activation status of the coagulation system. Hence the aim of this study was to compare plasma levels of activated factor VII (FVIIa) in men and women, and to study the influence of the menstrual cycle on FVIIa levels. In a prospective study we investigated 20 healthy young women and 20 men. Men had significantly higher levels of activated factor VII (60 mU/ml, CI: 52 to 67) than women during all phases of the menstrual cycle. In women FVIIa was higher during the follicular phase (41 mU/ml, CI: 33 to 50) than during midcycle (34 mU/ml, CI: 24 to 45; p = 0.022 vs. follicular phase) and during the luteal phase (33 mU/ml, CI: 24 to 42; p = 0.006 vs. follicular phase). Prothrombin fragment (F1 + 2) levels decreased from 0.86 nmol/l (CI: 0.51-1.21) by -23% (-39% to -8%; p = 0.011) during midcycle and by -25% (CI: -51% to 1%; p = 0.023) during the luteal phase. These data support the contention that plasma levels of FVIIa, a key enzyme of the coagulation cascade, may be down-regulated by endogenously produced female sex hormones during the menstrual cycle. This may at least partially explain the marked gender differences found in FVIIa.