When I started estrogen, I knew my penis would flounder and I’d grow breasts (awesome!). Every community of trans women within reach was replete with discussions about the usual suspects: breast development; fat redistribution; reduced body hair growth. These are well-known effects of feminizing hormone replacement therapy (HRT).

What surprises me is just how much other stuff is managed by primary sex hormones. The EPA (bless their hearts under this administration) notes that there are over 50 hormones in humans. Most of them serve a regulatory purpose. Some of them are necessary for life. Estrogen and its manly counterpart are only two of those, but their overabundance or deficiency can change the entire experience of living.

So here’s my I Lived It story about unexpected things that happened to me (and others) who started feminizing HRT.

1. I’m so much cooler these days

Literally and figuratively.

There’s this physiological quirk where on average, men work more comfortably in cooler temperatures than women and cis women are sometimes shown to be more sensitive to temperature changes than cis men. Recent research has extended this temperature sensitivity to trans women on feminizing HRT. And what does this research prove? That my feet are cold. Although I already knew.

As estrogen took effect, my experience of temperature changed. I run cooler than I used to. I get cold more easily, and need more layers to feel comfortable. Most importantly, I can handle heat better than I used to. Despite naming myself Summer, I used to hate the warm half of the year. I now find heat tolerable, although humanity’s collective efforts push my limits every day.

The relationship between sex hormones and temperature is wild. People have argued that office air conditioning is sexist due to its discomforting effect on women. Menopausal hot flashes are strongly associated with a decline in estrogen production. There’s even a hypothesis that clothing habits of trans women like tucking may increase scrotal temperatures, which reduces our sperm quality. Hilarious, since nothing kills our sperm faster than estrogen in the first place.

No, there isn’t enough research on this topic to establish a scientific consensus. Much of it is anecdotal. What I can say for myself is that I love cool environments. I have nerve damage that impairs sweat production, so I overheat faster than almost anyone. Estrogen made my body run cooler to counteract the nerve damage and I finally feel normal.

2. My veins don’t pop as much

This one was circulating (heh) on Reddit early in my transition. The prospect excited me. Visible vascularity is the veininess you see under the skin. Some of it criss-crosses directly under the surface. It’s especially visible in high blood flow areas like the feet or on flexed muscles. The latter part explains its association with fitness and bodybuilding.

The association of vascularity with muscularity and strength ran counter to my personal transition goals. I’m preoccupied with daintiness to a fault. The prominent veins cutting across my forearm and shin were a bug, not a feature.

Estrogen addressed that. My veins are much less visible than they used to be and it comforts that soft spot in my self-esteem. My thinking brain knows that all bodies have veins and they all look different, but it’s hard to shake some of the self-talk.

For a more informed take, Dr. Anastacia Tomson (general physician, activist, and fellow estronaut) says, “Lower body temperatures result in less vasodilation (that is to say, the blood vessels under the surface of the skin do not expand as much as they would under testosterone).”

3. Peeing yourself a little bit. Forever

Within months of my first dose, I saw a reduction in muscle mass. Expected. I also started peeing myself a tiny bit after every trip to the bathroom. Every single one. Less expected. The standard twist-and-shake was no longer sufficient. I wrang my penis for a few more drops. I worked my kegel muscles. I started wiping and leaning forward to get gravity in on the action. Once satisfied, I’d get my clothes back on, wash up, and leave.

Then pee myself a bit as soon as I sat down.

Dr Tomson’s fancy word version is that, “Estrogen can cause changes to skeletal muscle in terms of mass and strength, and this includes the muscles of the pelvic floor, which could lead to certain kinds of incontinence.”

That’s very unfortunate for my thirty year-old ass because incontinence is a word I associate with people who are much younger, older, or unluckier than me. Sadly, my girlfriend, our girl bestie, and an assortment of women in my life have verified this. They all pee themselves a bit after we think we’re done. I just arrived late to the party.

4. Dying but in a girlypop way

Hormones are intimately linked to disease risk. I mean, numerous conditions just happen because of hormone imbalances. Most of them make life awful. Some of them make life awful, then kill you.

Besides all the other stuff, primary sex hormones can alter a person’s risk profile for various diseases. Early research suggests that trans women on estrogen and anti-androgens have a five times lower prostate cancer risk. This coincides with the use of antiandrogens to inhibit prostate cancer in cis men.

Estrogen gave me breasts, but my girlfriend gave me a crash course on the self breast exam. Because guess what? Having breasts significantly increases the risk of breast cancer. Including for trans women.

Taking estrogen orally (usually via a pill) is also loosely linked to an increased risk of cardiovascular illness in trans women. But this possible negative side effect doesn’t amount to a meaningful argument against feminizing HRT. All HRT, anti-androgens, and puberty-blockers have long histories of use in cisgender populations and their application to trans bodies is merely a matter of equal access to healthcare.

The research seems to mirror Dr. Tomson’s best guess about risk profiles, which was, “Overall cardiovascular risk decreases, and we expect (but have not proven) that prostate cancer risk will also drop. The risk of developing blood clots may increase with certain forms of feminising HRT, and ostensibly the risk of breast cancer can increase too.”

When I started estrogen, my informed consent documentation highlighted these risks. I signed off anyway. In hindsight, one of my strangest sources of gender affirmation has been knowing that I’m much more likely to die ‘like a woman’. That’s comforting… I think.

Hormones: One cause of, and solution to, all of life’s problems

This sourced list doesn’t cover half of it. Some notable runners-up included feminizing HRT’s ability to halt or reverse androgenic balding, scattered reports of sharper vision and smell, and reduced acne. Every study I found championed the need for more research into transgender endocrine health because it would improve healthcare delivery and reduce risks.

In my life, I’ve joined my cis girlfriend and girl friends in attributing the numerous physiological ills and gains to hormonal fluctuations. The more I read into the workings, the more I realize that I can blame anything that goes wrong in my body on sex hormones and have a decent shot at being right about it.

However, I’ve yet to find an explanation for people’s growing desire to hurl objects at Supreme Court buildings after major rulings that prohibit medical equity. Further data is required to establish a meaningful consensus on this phenomenon.

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