Hormone replacement therapy (HRT)

Hormone replacement therapy refers to the use of supplemental hormones to treat low testosterone or post-menopausal symptoms, due to lower estrogen. HRT can treat the symptoms of hypogonadism. HRT is also used by transgender people, to help them develop physical characteristics that reflect their gender. This is usually called gender-affirming hormone therapy (GAHT).

What is hormone replacement therapy?

Hormone replacement therapy (HRT) is a treatment that involves taking hormones to replace those that the body has stopped making or makes too little of. While HRT is often used to refer to treatment with sex hormones like testosterone and estrogen, it may also include hormones involved with the thyroid or pituitary gland.

Hormones can be delivered to the body in a number of ways, including injections, pellets, patches, or gels. In traditional HRT, the hormones taken are synthetic (made in a lab). In bioidentical hormone replacement therapy, hormones are derived from plant estrogens that are chemically identical to those the human body produces.

Types of hormone replacement therapy

Some people use HRT to offset the side effects associated with aging and reduced levels of sex hormones, susch as estrogen or testosterone, in the bloodstream. This may occur during or after menopause (for people with ovaries) or simply with age (for people with testes). Low testotserone or estrogen may contribute to reduced sexual function, decreased energy levels, weight gain, depression, risk of osteoporosis, and more.

Estrogen therapy is a type of HRT that helps alleviate some of the negative symptoms of menopause, such as reduced libido, hot flashes, night sweats, mood changes, and more. It may also prevent bone loss and reduce fracture in postmenopausal women.

Sometimes called androgen replacement therapy, testosterone replacement therapy treats testosterone deficiency in cisgender men. TRT is a form of HRT specifically used to address male hypogonadism, in which a problem with the testicles or pituitary gland causes the body to produce too-low levels of testosterone.

In gender-affirming hormone replacement therapy (GAHT), transgender or gender-expansive patients are treated with hormones and other medications that help them develop physical characteristics to match their gender identity. In feminizing hormone therapy, individuals may be given testosterone blockers along with estrogen. In masculinizing hormone therapy, individuals may receive testosterone.

Hormone replacement therapy and fertility

For premenopausal people with ovaries, taking estrogen or progesterone can help correct irregular ovulatory cycles and imbalances, creating a more ideal ovarian and uterine environment for a pregnancy to occur.

Conversely, for people with testes, taking supplemental testosterone can be detrimental to fertility. Exogenous (meaning added) testosterone affects the hypothalamic-pituitary gonadal axis, shutting down the production of other hormones that are essential for sperm development. Studies show that testosterone replacement therapy can halt sperm production altogether, though the effect is typically temporary.
Transgender individuals who undergo gender-affirming hormone therapy are also at risk for infertility. Research shows that testosterone therapy in transgender men can suppress ovulation, while estrogen therapy in transgender women can result in impaired spermatogenesis and testicular atrophy. This is why transgender patients are often encouraged to consider sperm freezing or egg freezing to preserve their fertility options.

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