New clinical findings from Dr. Will Powers: Role of estradiol/estrone ratio in the efficacy of feminizing HRT

(Epistemic status: Extremely tentative.)

Dr. Will Powers, an HRT provider in Michigan who has possibly the coolest name ever, has recently posted a slideshow outlining findings from his practice on the most effective approaches to feminizing hormone therapy for trans women. Briefly, Dr. Powers has observed that inadequate feminization may be related to imbalances in levels of estradiol (E2) and estrone (E1), a form of estrogen which also binds to estrogen receptors but is much weaker in its effects than estradiol. Readings of total estrogen may indicate that overall levels are in the desired clinical range, yet within this total measurement, E2 may be too low, while E1 is too high. Powers notes that E1 “competes with estradiol for effect” at estrogen receptors, and because of the relative weakness of E1, this imbalance may slow the process of feminization (p. 24).

What can be done about this? Powers recommends starting with oral estradiol taken buccally (absorbed through the gum line) or sublingually (absorbed under the tongue), which he finds to produce a better ratio of estradiol to estrone. If this fails to produce estradiol-dominant levels, his protocol is to switch to long-acting injectable estrogen or transdermal estrogen patches. This may reflect common anecdotal reports from trans women of achieving more effective feminization from injections. Powers has stated that about one-third of the trans women he treats exhibit an undesirable balance toward estrone, and that he has applied this estradiol-dominant protocol successfully in 30 to 40 trans women, with “increased feminization facially as well as breast development and adipose redistribution” (p. 26).

While much of this is clearly highly speculative and in need of further rigorous study, Powers states that he will soon be publishing his findings. Should this pan out, these new findings may help clarify the endocrinological processes involved in hormonal transition for trans women, and could point the way to the development of more effective hormone regimens. I’ll be keeping an eye on this. 

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About Zinnia Jones

My work focuses on insights to be found across transgender healthcare, public health, psychiatry, and history of medicine, integrating these many perspectives and guided by the lived experiences of trans people. I live in Orlando with my family, and work mainly in technical writing.
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