Estrogen and Hair Growth

For the male readers of this blog, estrogen (also known as oestrogen) is not something that one would consider to be of any interest upon first glance.  For one, estrogen is a female hormone, so what male in his right mind would want to start taking estrogen and getting female secondary sexual characteristics and increased fat deposits  among other side effects?! Estrogen does have some beneficial properties for the heart, and is though to be one of the main reasons behind why females outlive males. However, I would still pass on it.

The reason I decided to write a post on estrogen, however, is because I recently read an extremely interesting 4 page interview from 2012 of our omniscient hair loss hero Dr. George Cotsarelis. While the main part of the interview is devoted to the oft discussed PGD2, there are a few other interesting subjects discussed.  The second page of the interview is what really surprised me in a good way.

On page 1 of this interview, Dr. Cotsarelis discusses the old and well known Dr. James Hamilton study from the 1950s in which it was found that men who were castrated before puberty (eunuchs) never went bald, but upon being given testosterone, those with a family history of baldness still started to loose hair.

On page 2, however, Dr. Cotsarelis mentions something that I had never read before and that got me quite excited: basically, even after someone has lost much of their hair due to androgenic alopecia, they can regrow a lot of it when given estrogen after castration!  His point is supposedly verified by many studies on transgender (I assume male-to-female, aka MTF) patients showing hair regrowth after their being castrated and getting on estrogen therapy.  While I do not think any of us men want to get castrated or take estrogen, this is still an incredible finding.

Over the years, I have read a number of articles in which doctors and professionals seem to suggest that once hair is gone (turns vellus/becomes extremely fine), it can never return.  This is also why Finasteride and Minoxidil virtually never get back any significant amount of hair for someone who is mostly or entirely bald.  There have been anecdotal posts on internet forums about Dutasteride actually regrowing large quantities of vellus/invisible-to-the-eye hair, but these have been few and far between.  Over a decade ago, Dr. Marty Sawaya caused an insane level of excitement on hair loss forums when she reported that one of her older patients gained back most of his long lost hair when on Dutasteride, but that whole episode was controversial and not replicated.

More recent research has suggested that a balding scalp still has all the follicle stem cells intact, but certain progenitor cells have become depleted.  Basically, the cells are there, but the activity is not there.  In this 2012 interview, towards the end Dr. Cotsarelis mentions that perhaps blocking PGD2 will allow the stem cells to make progenitor cells again.   However, this is not a certainty, and neither is there a given that long lost hairs will regrow again once PGD2 is inhibited.

I suspect that this powerful impact of estrogen on hair regrowth is still not strong enough to grow back all of one’s lost hair, since many/most older balding MTF transsexuals seem to get hair transplants even after getting castrated and getting on estrogen therapy.  I was planning to write a couple of posts on MTF transsexuals this year, and hopefully I can get more direct feedback from some of them on this highly interesting issue.

Another important thing that Dr. Cotsarelis mentions on page 2 is that there could be an inflammatory component to hair loss.  This also surprised me, because he seemed to be saying the opposite just two years later when being interviewed in 2014 (in response to Dr. Brett King’s groundbreaking results in curing alopecia areata) when he said that androgenic hair loss probably does not have an immune system component to it like alopecia areata.  Am I misunderstanding something here in the contradiction?  Doesn’t an immune system attack imply inflammation?

Finally, for men who take Finasteride (brand names Propecia, Proscar, Finpecia, Fincar etc…), one potential side effect is increased estrogen levels, which sometimes results in the dreaded gynecomastia along with fat gain in other body areas.   Their are numerous complaints on hair loss forums about this.  So besides the fact that estrogen therapy is not of much use unless you get castrated, another reason for a man not to take estrogen in the hopes of growing back some hair is…. man-boobs.