TL/DR It's difficult to be brief related to topical estrogen and estradiol levels in general but topicals will most likely only fully or even partially restore a head of hair when their use results in estradiol levels of at least 200pg/ml. Nevertheless, estrogen topicals might have localized effects and still be useful for hair improvement/maintenance.
Your understanding of the issues related to estriol essentially blocking out estradiol in some contexts but not in others is consistent with what I have read and consistent with my own results body-wise. Some conjecture that estriol doesn't attach to breast growth receptors and thus acts as a sort of Serm that out-competes other estrogens (and there are many) related to breasts while still having a prevalence to attach to receptors related to hair growth/regrowth. Like the prostaglandin flow charts which many people whom I respect claim show that they should work to regrow hair, I am dubious about estriol because it is so weak. Yes, it can work to attach to hair receptors but you have to use so much (loads) that this is mostly for the advanced folks who make their own meds and who eschew any feminization at all, while possibly also using AA's.
And good for them, we all learn by each other's trials and I follow attempts with just estriol closely but for most folks this is not practical and it presents pretty strong limits related to hair restoration which can be significant in a male-context but not even close to significant for those transitioning to female and probably not most males.
One of the best restoration pics on the net before
@bridgeburn's results is an MtF who still is nowhere close to get tingout of her wig and she might not ever but hair results can continue for years for MtF's. Then again she started off as a slick bald horseshoe and
@bridgeburn at least had decent fringe and maybe half or a third of his hair on top but he was clearly headed to horse-shoe slick baldness without HRT. But this gal, who had maybe restored half of her hair, still wasn't close to even appearing to be a non-balding male. She had sort of Julius Caesar or Napoleon-type hair. Even for an XY, it barely improved her looks although this is subjective. It was unacceptable for virtually all MtF's except for those who present as male which is confusing, I know, but MtF is often now used to indicate hormonal direction not gender status and that is true for me as non-binary seeking androgyny. So an XY using female HRT is an MtF in terms of medication approach but might still prefer to be seen as a male or lesbian or androgynous. It's confusing even for us which is why I often use the terms XY or XY-female. But I digress.
As a practical matter for most of us, I think estriol is still feminizing both instantly and over time but strangely enough, it might be better for MtF's who have to concurrently manage breast growth and hair growth or to do as I have and focus on breast growth for say, three years and then focus on hair growth. The approaches are subtly different and there are traps for cis-guys regardless of dosage, low or high. This has to do with low amounts of estrogens mimicking the start of cis-female puberty where the body gets this low estrogen feedback and immediately "turns on" breast growth based upon what it deems to be pubertal growth signals related to initiating breast growth. MtF's who start at too high levels of estradiol and AA's might in essence "skip" this second puberty, as it is commonly known, and miss the prime breast growth years. Anyway, I used pretty much only used estriol when just starting out but then used much more so, the Biestro blend from Life Flo on Amazon and I am the walking poster boy/girl for sometimes, yes, XY's can experience significant cis-female breast growth but this is pretty rare. The average cup size for MtF's is double A, which to me, virtually everyone would accept for a full head of gorgeous hair in the abstract. So personal risk/reward analysis is necessary before using even low-dose estrogens.
So now we are left with two issues. Does Biestro/Estrogel work better when used on the scalp and will it regrow/improve hair? I am uncertain as to whether scalp distribution of Biestro/Estrogel works better for hair improvement/restoration. Topicals often can be more efficient related to having effects on localized tissue. One assumes that is why we put topical minoxidil on the scalp but it seems not to go systemic to a large extent. Estrogen does go systemic and fairly strongly. I recently posted an article above where the plates/dates guy disparages its use on the scalp and he could be right. But then again, things like scalp thickness, scalp fat, scalp microflora, etc. can all be important factors and that is why anecdotal reviews are often not worthwhile. Sometimes they are great though when we have little other basis for dosaging information like for cis-guys starting HRT. 2 to 4 mg of estradiol seems to be the sweet sport when combined with an AA and in the longer-run, even 2 mg of estradiol might work.
Now, let's focus on whether Biestro works on hair. It's easy to get and re-order and you get it in two days or less. I put my money where my mouth is as Amazon indicates that I have bought Life Flo Estrogen products over 100 times since 2013. The estriol in my view is too weak and I only use it in emergencies, if it is all that I can find. Once I lost my credit card so Amazon was out and Ebay only had estriol on offer so I bought that. The estradiol version is more expensive and only carries half the volume by weight of the Biestro product so I went through that too quickly and kept having to re-order too much. Even with HRT estrogen in pill form, I continued with the Life Flo Products until I found a reasonable source for Estrogel without a prescription where they take credit cards, which is one vendor in Thailand, known strangely enough as Amazon4Health but not related to Amazon. (Trademark enforcement in Thailand seems to be weak). A list of all off-shore vendors that are reputable can be found here, by either clicking or pasting, HRT.cafe, no com needed.
I think that estrogen works when used on the scalp without doubt. Now whether using it on the testicles where absorption is more efficient and streamlined would work better, we don't know but probably since it creates higher E levels. But since the estrogen on the scalp essentially gets two shots at the apple, both topically and systemically, we just don't appear to know. People I respect both believe in localized effects and others I respect say that the data are weak related to localized effects on MtFs. Reddit has a great source called Transfeminine Science that I hold in high regard. Others like Dr. Will Powers, eh. Sometimes he is right. If you look here at my hair and transition blog, I have five years of hair and beard/dermatitis pics up and I can see real improvements during the times that I used copious amounts of Biestro followed by periods of retreat when I went off them because of family pressure, etc.
Here's how I think Biestro and Estrogel might/probably work. Initially, they cause subtle improvements to hair related to hair memory, i.e. maintaining a part in the wind and looking less disheveled without a comb. There seems to be a subtle increase then in ability to grow hair long, followed by a subtle by general improvement in hair quality. In my pics from October 2017 on the blog, I think I point out these improvements from baseline which happened about a year before my massive shed, which is a different era for me, because I had started with a doctor and actual prescribed HRT meds and my hair then actually got worse when I stopped using Biestro, probably because my oral E dosage was tiny, at .30 mg Premarin. We titrated upwards to 1.25 mg daily of Premarin (still a tiny dose) and then added quickly 100 mg of spironolactone and then 200mg of spironolactone, which I often exceeded going to 300 mg to 400 mg at times with my additional off-shore supply of spironolactone. Then bam came the massive shed to baldness which makes me wary of sheds especially for cis-guys. I could wait it out under a wig but cis-guys generally eschew wigs or hair systems.
Estradiol to me follows a linear curve that appears to become more steep in terms of effectiveness over time and especially as doses are titrated upwards. When a person reaches adult cis-female levels of E2 and T, some studies indicate that hair regrowth is essentially "turned on" and so these levels of estradiol might be a requirement for good hair results, so then at 200 pico-grams per milliliter to 300 pg/ml, hair growth commences in a copious way and restoration for people with extremely thin but not horse-shoe hair can continue for up to 18 months quickly and then level off and improve gradually again over time.
So, yes, in my opinion Life Flo Biestro works very well for hair as a conditioner and a marginal improvement vector which progresses incrementally but for the
@bridgeburn wonderous results, I think folks need to shoot for at least 200 pg/ml which is highly feminizing. I had expected Life Flo and Estrogel to work much better with middling levels of both T and E2 which I had until last June. Middling levels of E2 and T are find for body feminization but for some reason, above the neck feminization both facially and in terms of hair improvement come last and you have to go through the breast growth phase to hit the hair restoration phase.
So there is a reason why HRT for cis-guys is generally not a thing besides temporary infertility and perhaps impotence. It's because you have to progress so far as an MtF to get the great hair and the marginal improvements that I had, folks will have to look for themselves and decide if they are worth the cost and yes, extreme effort as I massaged these meds twice daily and monitored their use extensively. finasteride and oral minoxidil now appear to me to be a better route for cis-guys for regrowth and not simply maintenance due to oral minoxidil's efficiency. Biestro might work very well at lower doses for maintenance but again, you have to monitor the situation closely and for many folks even twice a day application of topical min is too much of a hassle. This is a down-grading and an upgrading of my estimation of topical estrogen relative to hitting adult female target levels. All thing being equal,
ceteris paribus, I continue to believe in topical effects and people whom I respect, some of them do as well but for something like
@bridgeburn's results you have to be all in. He used large amounts of AA's, sublingual estradiol tabs and oral and topical minoxidil plus ten days a month of progesterone which is similar to my regime with even the progesterone but I use medroxyprogesterone acetate instead of an AA, as I find it more reliable and without jarring effects or sides like bica, CPA and spironolactone.
Goddess Bless.
pubmed.ncbi.nlm.nih.gov
