I think this conclusion is incredibly naïve given the dramatically increased bioavailability and significantly decreased side effects that sublingual administration has over oral estradiol. Flooding the liver through oral administration results in strain that is significantly reduced by sublingual administration, and the increased bioavailability alone accounted for comparable testosterone suppression without an anti-androgen at the same daily dosage. So on top of the decrease in liver damage by moving away from oral administration, this approach also does not account for the side effects of the anti-androgen. The miniscule sample size doesn’t do any favors to this study, either. The supposed “alarming excursions of serum estradiol” is solved simply by adjusting the dosage and spreading it out into more frequent doses throughout the day. It seems they did split the dosage into 4 doses for sublingual administration, but they are providing the same daily dosage despite significantly increased bioavailability of the sublingual route (which also accounts for the testosterone suppression). Additionally, a dosage of only 2mg of estradiol daily via oral administration is quite low for trans women.

I have a lot of problems with the conclusions of this study.

I’d like to link to a much more complete analysis of the sublingual route of administration for estradiol that analyzes a wide variety of sources (including the one linked in this post) for those interested in a more accurate picture of the benefits and shortcomings of sublingual administration:

An Exploration of Sublingual Estradiol as an Alternative to Oral Estradiol in Transfeminine People

While I’m aware that sublingual requires a much lower dosage, and obviously oral has the disadvantage of liver strain from estrogen flooding, did you find data that actually empirically analyzes the feminizing efficacy of oral vs sublingual? Or are you just referring to the difference in dosage?