Thread by @Generic_Bi

0) I have a bit of time this evening, so here is how the HPG axis works. There are a lot of acronyms, so I’m dropping an image of the HPG axis here, but it basically makes a loop of H to P to G and back to H, keeping everything in balance. (I’m just focusing on puberty here)

0.5) Also, I’m calling it a night, so I can’t respond immediately. I hope I’ve worded everything respectfully and appropriately.

If you are here to attack trans people, you can set that aside and read, choose kindness, or move along.

#BWithTheT #LGBWithTheT #protecttranskids

1) The hypothalamus (a part of the brain just north of the pituitary) has a group of cells with estrogen receptors, and as long as estrogen/testosterone isn’t present, release Gonadotropin-Releasing Hormone (GnRH).

2) Before puberty, the hypothalamus is extremely sensitive to the presence of estrogen or testosterone, which prevents puberty from starting too early. When puberty begins, this negative feedback loop gets scaled to adult levels, and the pituitary gland gets its signals.

3) The pituitary, when it detects GnRH, releases Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH). This is where puberty blockers act. They bind the GnRH receptors in the pituitary, and prevent the gland from releasing these FSH and LH.

4) FSH, in puberty, cause primordial germ cells to mature, while LH stimulates both the ovaries and testes to produce testosterone. Testosterone, the precursor for estrogen, is largely metabolized in ovaries into estrogen. These drive development of secondary sex characteristics.

5) After production, these hormones help support growth of reproductive cells, but they don’t stick around for long. Both testosterone and estrogen are transported out of the gonads, and it is a one way trip, no re-entry.

6) As they circulate in the body, some will bind to receptors in the hypothalamus, and if the level of either of these hormones is above a certain level, GnRH release is blocked. There is similar negative feedback loop to the pituitary as well. Think… sex hormone thermostat.

7) If someone enters puberty early, there are negative physical and social effects, and puberty blockers are used to delay puberty for a few years. The effect is 100% reversible, and after stopping these drugs, puberty can start again.

8) There is no evidence that this affects fertility, as patients who used puberty blockers to delay puberty have normal rates of successful pregnancies for females, and normal sperm production for males.

9) For patients that are trans or suspect that they are trans, delaying an entry into puberty improves mental health outcomes and provides enough breathing space to seek treatment and counseling, at least in nations with functional health care systems.

10) With some time, if they decide that they want to allow puberty to proceed as normal, they can do so.

If they choose not to, they can begin hormone replacement therapy (HRT), which will direct the body to develop accordingly.

11) Instead of preventing hormone release at the pituitary (as GnRH blockers do) testosterone and estrogen produced outside the body acts at the hypothalamus to prevent release of the hormones that affect germ cells. They don’t cause development of germ cells.

12) If someone who has been on puberty blockers, followed by hormone replacement therapy, were to stop HRT, their hypothalamus sees no sex hormones and tells the pituitary to direct the gonads to get to work making them, and fertility is restored.

13) A year, a decade, a few decades, the gonads really don’t care. They get the signal and start doing their job, and based on the evidence we have, the only lost fertility is that set aside by choice and bodily autonomy.

In this, it’s similar to the birth control pill.

14) The lives preserved by having control of one’s body, having supportive family and friends, and responsive and compassionate medical care are where fertility can exist.

If your concerns don’t include suicide prevention, your interest in fertility is hollow.

15) Now, if someone chooses to have a surgery that is sterilizing, adults can do that. Up to that point, hormone blockers and hormone replacement are reversible.

16) This review article is a good summary of the field, and should be free to view.

karger.com/Article/FullTe…