While this applies only to a small subset of menopausal individuals, we some time back, now, read two interesting research articles about ethinyl estradiol, a synthetic estradiol used most typically in oral contraceptives but also used by some of those in menopause who specifically need a synthetic estradiol.
In the first study, "Formation of Ethinyl Estradiol in Women during Treatment with Norethindrone Acetate," it appears that taking this progestin, used by some to suppress endo in surgical menopause, allows the body to create this form of estrogen (that is, it's partly metabolized into this estrogen). The implication, we think, is that a user's's total estrogen exposure might thus be miscalculated. That's not of functional significance unless one wants to avoid estrogen exposure or when a woman using NET-A changes HRTs and suddenly finds her estrogen needs seem wonky. How much? It's probably pretty individual, but point your endocrinologist to this article and ask for help with interpretation if this affects your HRT regimen and concerns.
In the second, "Effects of oral and trans-vaginal ethinyl estradiol on hemostatic factors and hepatic proteins in a randomized, cross-over study," researchers report that oral and vaginal delivery of ethinyl estradiol makes no difference in clotting risk factors. This is pretty much different from what current thinking is on other estrogens, where transdermal delivery is less stimulating of these factors when compared to oral delivery. Again, it's likely to affect only a few users, but it does suggest that those at higher risk for clotting (smokers, those with elevated cardiovascular risk profiles, or a stroke or clotting history) might want to consider other this estrogen for their HRTs, as might those who require an oral estrogen for some reason but are wary of the effects of oral estradiol or CEEs.
