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Hormone Replacement Therapy, also known as as Hormone Therapy, is intended to emulate the natural levels of sex hormones of either gender. For MtF's, this therapy is usually a combination of an estrogen and an anti-androgen. For FtM's the therapy usually includes testosterone.
As mentioned in the introduction, Hormone Therapy for MtF's includes both an estrogen and and anti-androgen. The estrogen is to emulate the natural levels of estrogen found in a woman. The anti-androgen is to combat the testosterone that is present. This is discontinued after an Orchiectomy or GRS, due to the lack of naturally produced testosterone.
It doesn't undo the existing masculinising effects of testosterone, but does cause the development of female secondary sex characteristics, such as breast growth and typical female fat distribution. It also carries with it a number of side effects and risks.
Common Drugs Used
- micronized estradiol
- estradiol acetate
- estradiol valerate
- estradiol cypionate
- estradiol enanthate
- conjugated estrogens
- esterified estrogens
- ethinyl estradiol
- Cyproterone acetate (More commonly used outside of the US.)
Effects of HRT
- Skin becomes softer.
- Sebaceous gland activity lessens which lowers the amount of sebum production on the skin, leading to a less prone to the formation of acne due to the less quantity of oil that is produced.
- The skin's pores become smaller due to the low quantities of sebum produced
- Body odor (skin, sweat, and urine) will become less "metallic," "sharp," or "acrid" and more "sweet" and "musky."
- Many apocrine glands (type of sweat glands) become inactive and body odor decreases. Sebum also contributes to body odor, the production of which is reduced by anti-androgens (as described above).
- Breast development
- The nipples will become more sensitive to stimulation.
- Breast, nipple, and areolar generally takes around 4–6 years to complete, depending upon genetics, and can take as long as 10 years.
- The size of the rib cage and shoulder width also play a role in the apparent "size" of the breasts
- Current facial hair is only slightly affected (some reduction in density, coverage, and slower growth) by anti-androgens.
- Those taking anti-androgens will have better results with electrolysis/laser hair removal than those who are not.
- Body hair will, turn from terminal hairs to vellus hairs
- New head hairs may slightly change in texture, curl, and colour.
- Eyebrow hair becomes less "bushy" or scattered.
- Fat distribution
- The body will now tend to accumulate new fat in a typically female pattern. This includes the hips, thighs, buttocks, pubis, upper arms, and breasts. The body will now tend to use the existing fat in the waist, making the waist appear.
- Subcutaneous fat increases in the cheeks and lips making the face appear puffier, appearing to round out the face.
Side Effects and Risks
There are many possible side effects related to HRT. Some are related to the estrogens, some to the anti-androgens. This is be no means an exhaustive list, but it does cover all the basics.
- Increased blood clotting due estrogens. This leads an increased risk for thromboembolic diseases such as deep venous thrombosis and pulmonary embolism.
- It is accepted that smoking and age are likely to increase the chances of DVT.
- Oral estrogens are also more likely to cause DVT, rather than implantable, injectable or transdermal estrogens.
- The Bladder atrophies
- The Prostate atrophies
- The perineal raphe, line that runs down the underside of the penis and down the middle of the scrotum, will darken.
- Minor water retention is likely
- There is sometimes a reduction in libido, depending upon the dosage of anti-androgens.
- Spontaneous and morning erections decrease in frequency significantly, however some who have had an orchiectomy still experience morning erections.
- The testes atrophy by as much as 50%, depending on anti-androgen dosages.
For hormone therapy in FtM's, the primary, and often, only thing prescribed is testosterone. This can be delivered as in injection, transdermal patch, orally or sub-lingually. As with MtF hormone therapies, it is not without risk.
Effects of HRT
- an enlargement of the clitoris
- redistribution of body fat,
- growth of facial and body hair
- deepening of the voice
- male pattern baldness, in some
- possible shrinking and/or softening of breasts, mostly due to changes in fat tissue
- increased libido
- increased red blood cell count
- cessation of ovulation and menstruation,
- further muscle development, especially upper body
- increased sweat and changes in body odour
- coarser skin and acne (especially in the first few years of therapy)
- alterations in cholesterol and triglyceride levels
Side Effects and Risks
- Testosterone can cause weight gain and decreased insulin sensitivity
- Testosterone redistributes the fat toward abdominal obesity, leading to increased cardiovascular risk
- Testosterone also adversely affects the blood lipid profile by causing decreases in good cholesterol and increases bad cholesterol and triglycerides
- Supra-physiological levels of androgens (generally due to abuse) are associated with significantly increased risks of strokes and heart attacks (even in the young.) More is not better!
- The most important modifiable risk factor for many men is smoking.
- The action of testosterone on hair follicles is mainly due to the more potent androgen, dihydrotestosterone, DHT.
- With androgen therapy, genetics primarily determines how much hair will develop (and where) as well as whether male pattern baldness will develop.
- Testosterone is converted (within the cells of the hair follicle's dermal papilla) by 5-alpha reductase to DHT.
- Gynecological effects
- Menses should cease within 5 months of testosterone therapy (often sooner.) If bleeding continues past 5 months, trans men must see a gynecologist.
- Clitoromegaly occurs, and frequently reaches its apex within 2-3 years of therapy. Sizes generally range from 3-8 cm with 4-5 cm being about average. This is genetically determined, but some physicians advocate topical clitoral testosterone as an adjunct to growth before metoidioplasty.
- It is unknown whether the risk of ovarian cancer is increased, decreased or unchanged in transgender men compared to women.
- Some transgender men report a decrease in breast size with androgen therapy. This is likely it is due to loss of fat in the breasts.
- Most transgender men report a significantly increased libido.