Our results show that progesterone is safe and effective for transgender people. We’re now able to prescribe it, in a trial setting, for those who have been taking oestradiol for at least year. We hope that our findings lead to better hormone treatments for transgender individuals." Koen Dreijerink, endocrinologist at Amsterdam UMC
Comment repost by /u/Impossible_PhD
Hi folks! Since this is a preprint, and we don’t have their full ms results available to look at, I dug up the study recruitment info. This is an interesting result, but I’ve got a few cautions. Here’s what you need to know:
- This is a complex RCT, meaning there wasn’t just one test and one control group, there were three of each. Complex RCTs can be fine, but they’re inherently more vulnerable to independent variables, which means they’re more likely to return false positives or false negatives.
- Complex RCTs are at their best as building blocks, IMO: by testing more stuff, you find the most promising things to test for later, larger simple RCTs.
- The study has an already-small participant pool (90 people), but it being a complex RCT means that there were only fifteen participants per test/control group.This is an EXTREMELY small sample group, and highly vulnerable to false positives or negatives.
- They measured differences in both estrogen dose and progesterone dose in this study, and the lower-estrogen “control” (there isn’t a traditional control group) was defined as having mid-cycle levels at 100pg/nl, or 400pmol/l. That means that half the time, that group was below target ranges for estrogen, so it’s absolutely no surprise that the study found that higher estrogen levels meant more breast development.
- The lowest dose of progesterone they measured was 100mg. Progesterone has a 90-minute elimination half-life. That means that, by the time a person at 100mg takes a new dose, they have–wait for it–only 0.00152mg of progesterone remaining in their bloodstream. With any drug that gets used up so quickly, it’s always hard to track cumulative long-term effects, such as breast development, which is a really big reason that studies on prog and breast development have been so all over the place (what few there have been, anyway). Until we have a longer-lasting, safe ester, so a dose isn’t eliminated so quickly, we’re gonna have problems being sure about these sorts of effects.
Anyway, bottom line: this is an interesting piece of research, and using 3D imaging here is probably the best way for them to monitor breast development. Unfortunately, this is really a prospective study, not anything even REMOTELY definitive, and it’s results shouldn’t be taken as such.
They’re not really trying to really determine whether prog makes your boobs grow here. They’re trying to find the doses most promising for a larger study, later, where they might be able to actually say whether prog makes your boobs grow. Honestly, the part I’m more excited by is that this shows evidence that underdosing estrogen at the Endocrine Society-recommended levels, is slowing feminization, and we desperately need results that say that stuff so we can do away with those guidelines.
Still, it’s exciting and promising! ⏤ by Impossible_PhD
This post and comment reminds me of something I’ve been wondering about and maybe can get an answer on from someone here.
I notice more tenderness in my breasts when I take oestradiol sublingually all at once rather than spread out over the day. Usually at night and tenderness comes the following evening. I’ve been taking it to mean that this regimen is better for my breast growth. I figure because it more naturally mimics the fluctuating levels cis women have iirc.
I also notice that at larger dosages help, but with too large dosages this effect goes away. I know that more does not always mean better when it comes to pharmaceuticals, and have wondered if perhaps slightly less than adult/maximal oestrogen levels (but not low or underdosed) with completely suppressed T mimics puberty closer and is more conductive to breast growth?
The tenderness hits even harder for a while if I switch to spread-out dosing for a while and then go back to all-at-once.
I may be wrong in every one of those assumptions, but the point of me asking is to figure that out. Does anyone know more?
- Does this tenderness actually indicate breast growth and am I right to try to maximize it?
- I have heard progesterone finishes off the last stages breast development, which is why I’ve been putting it off and letting them grow as much as possible. Is this correct? Is it possible to wait too long?
- Are there any studies on, or reliable methods for maximizing breast growth during transition?
Any help appreciated. Thanks
The largest increase was seen in the group who also increased their oestradiol dosage with some frequent side effects such as short-lasting tiredness, breast and nipple sensitivity and mood swings.
would be nice to actually read about the trial … should be stated, this isn’t published yet, hasn’t been peer reviewed, and doesn’t constitute a strong body of evidence (yet)
but it makes sense that the consistent anecdotal experience of many trans women that progesterone increases breast growth might eventually be demonstrated empirically 😅
A note for those in the Netherlands who want it officially (so not really DIY, but whatever…):
Apparently they will prescribe it, but only if you explicitly want it for breast growth. All the other reasons are nor sufficient justification, so if you are trying to convince your endo to give it to you, try that angle! (That’s at least what my GF who has now received it told me about her interactions, I’ll have my call about it on Christmas Eve, so let’s see about it then.)
