Hormone replacement therapy (male-to-female)
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Male-to-female hormone replacement therapy (MTF HRT) is a type of hormone replacement therapy for transgender and transsexual people. It changes the balance of sex hormones in the body. Some intersex people also receive HRT, either starting in childhood to confirm the assigned sex, or later if the assignment proves to be incorrect.
The purpose of hormone replacement therapy is to cause the development of the secondary sex characteristics of the desired sex. It cannot undo many of the changes produced by naturally occurring puberty, which may necessitate surgery and/or epilation (see below).
- 1 Formal requirements
- 2 Accessibility of HRT
- 3 Contraindications
- 4 Types of therapy
- 5 Overall effects of HRT
- 6 Cardiovascular effects
- 7 Hair changes
- 8 Urogynecological changes
- 9 Bone changes
- 10 Skin and eye changes
- 11 Fat distribution
- 12 Gastrointestinal and metabolic changes
- 13 Neurological and psychiatric changes
- 14 Hormone levels
- 15 See also
- 16 References
- 17 External links
The requirements for hormone replacement therapy vary widely. Often, psychological counseling is required.
The World Professional Association for Transgender Health (WPATH) recommends that individuals satisfy two sets of criteria—eligibility and readiness—to undertake any stage of transition, including hormone replacement therapy.
Eligibility is determined using a major diagnostic tool, such as ICD-10 or the Diagnostic and Statistical Manual of Mental Disorders (DSM).
- A transsexual identity for over two years
- A strong and persistent desire to live as a member of the opposite sex, usually accompanied by a desire to make one's body as congruent as possible with the preferred sex through surgery and hormone treatments
For a boy to be diagnosed with gender identity disorder of childhood under ICD-10 criteria, he must be pre-pubescent and have intense and persistent distress about being male. The distress must be present for at least six months. The child must either:
- Have a preoccupation with stereotypically female activities—as shown by cross-dressing, simulating female attire, or an intense desire to join in the games and pastimes of girls—and reject stereotypically male games and pastimes, or
- Have persistent denial relating to their male anatomy. This can be shown through a belief that they will grow up to be a woman, that their penis and/or testes are disgusting or will disappear, or that it would be better not to have a penis.
- Strong and persistent cross-gender identity: Adolescents and adults must display a persistent desire to be the other sex, frequent pass as the other sex, desire to live or be treated as the other sex, or believe that they have the typical feelings and reactions of the other sex. In children, cross-gender identity may be demonstrated by meeting the following criteria:
- An insistence that one is or desires to be the other sex.
- Children who seek a male-to-female transition must display a preference for cross-dressing or simulating female attire, and those who seek a female-to-male transition must persistently wear stereotypical male clothing.
- Persistent fantasies of being the other sex, or a strong and persistent preference for cross-sex roles in make-believe play.
- Intense desire to participate in stereotypical games of the other sex.
- Persistent discomfort with their sex or a sense of inappropriateness in the gender role of that sex. In children, this may involve disgust with the penis or testes, or a belief that they will disappear. In adults and adolescents, it may manifest as a preoccupation with removing primary or secondary sex characteristics through surgery or hormone replacement therapy.
- The disturbance must not be concurrent with a physical intersex condition.
- The disturbance must cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
The DSM-V replaced the term gender identity disorder with gender dysphoria to avoid the implication that gender nonconformity is in itself a mental disorder, but kept the entry so that individuals could still seek treatment. The DSM-V, unlike the DSM-IV and ICD-10, separates gender dysphoria from sexual paraphilias and diagnoses it on the basis of a strong conviction that one has feelings typical of the other sex, or a strong desire to be treated as the other sex or be rid of one's sex characteristics.
The second requirement for undertaking hormone replacement therapy is readiness. This means that the patient is likely to take hormones in a responsible manner; has made progress in addressing other identified problems, leading to improved or stable mental health; and has consolidated gender identity through psychotherapy or by life experience in their desired gender role.
Some organizations—but fewer than in the past—require, based on guidelines such as the Standards of Care for the Health of Transsexual, Transgender, and Gender Nonconforming People, that patients spend a certain period of time living in their desired gender role before starting hormone replacement therapy. This period is sometimes called real-life experience (RLE). The Endocrine Society stated in 2009 that individuals should either have a documented three months of RLE or undergo psychotherapy for a period of time specified by their mental health provider, usually a minimum of three months.
Transgender and gender non-conforming activists, such as Kate Bornstein, have asserted that RLE is psychologically harmful and is a form of "gatekeeping", effectively barring individuals from transitioning for as long as possible, if not permanently.
Accessibility of HRT
Some transgender people choose to self-administer hormone replacement medications, often because doctors have too little experience in this area, or because no doctor is available. Others self-administer because their doctor will not prescribe hormones without a letter from a psychotherapist stating that the patient meets the diagnostic criteria and is making an informed decision to transition. Many therapists require at least three months of continuous psychotherapy and/or real-life experience before they will write such a letter. Because many individuals must pay for evaluation and care out-of-pocket, costs can be prohibitive.
Access to medication can be poor even where health care is provided free. In a patient survey conducted by the United Kingdom's National Health Service in 2008, 5% of respondents acknowledged resorting to self-medication, and 46% were dissatisfied with the amount of time it took to receive hormone therapy. The report concluded in part: "The NHS must provide a service that is easy to access so that vulnerable patients do not feel forced to turn to DIY remedies such as buying drugs online with all the risks that entails. Patients must be able to access professional help and advice so that they can make informed decisions about their care, whether they wish to take the NHS or private route without putting their health and indeed their lives in danger." Self-administration of hormone replacement medications like estrogens (e.g., ethinyl estradiol) and antiandrogens (e.g., spironolactone, cyproterone acetate, flutamide, bicalutamide, and nilutamide), can cause elevated liver enzyme levels and other potentially dangerous side effects.
Some medical conditions may be a reason to withhold hormone replacement therapy because of the harm it could cause to the patient. Such interfering factors are described in medicine as contraindications.
Absolute contraindications—those that can cause life-threatening complications, and in which hormone replacement therapy should never be used—include histories of estrogen-sensitive cancer (e.g., breast cancer), thrombosis or embolism (unless the patient receives concurrent anticoagulants), or macroprolactinoma. In such cases, the patient should be monitored by an oncologist, hematologist or cardiologist, or neurologist, respectively.
Relative contraindications—in which the benefits of HRT may outweigh the risks, but caution should be used—include:
- Liver disease, kidney disease, heart disease, or stroke
- Risk factors for heart disease, such as high cholesterol, diabetes, obesity, or smoking
- Family history of breast cancer or thromboembolic disease
- Gallbladder disease
- Circulation or clotting conditions, such as peripheral vascular disease, polycythemia vera, sickle-cell anemia, paroxysmal nocturnal hemoglobinuria, hyperlipidemia, hypertension, factor V Leiden, prothrombin mutation, antiphospholipid antibodies, anticardiolipin antibodies, lupus anticoagulants, plasminogen or fibrinolysis disorders, protein C deficiency, protein S deficiency, or antithrombin III deficiency.
As dosages increase, risks increase as well. Therefore, patients with relative contraindications may start at low dosages and increase gradually.
Types of therapy
The most commonly prescribed estrogens in HRT for transgender women are micronized estradiol, certain estradiol esters such as estradiol valerate and estradiol cypionate (which are prodrugs of estradiol), and conjugated equine estrogens (Premarin). Estrogens may be administered orally, nasally, sublingually, by intramuscular injection, from an implant, or transdermally (via gel, spray, or patch).
Dosages for transgender people are often higher than replacement dosages for cisgender women. Hembree et al. (2009) recommend "maintain[ing] sex hormone levels within the normal range for the person’s desired gender". Dosages are typically reduced after an orchiectomy (removal of the testes) or sex reassignment surgery. However, that practice has been carried over from an era in which very high doses of estrogen were required to decrease testosterone, since antiandrogens were not used concurrently. Today, high doses of a less potent estrogen—estradiol, which is endogenous to the human body, rather than the riskier ethinyl estradiol and conjugated estrogens used in the past—are recommended during the first ten or so years of HRT, with or without an orchiectomy or sex reassignment. After that period, dosages can be reduced.
Progestogens include progesterone and progestins (synthetic progestogens). Progestogens commonly prescribed for transgender women include progesterone, cyproterone acetate, and medroxyprogesterone acetate. They may be administered orally, sublingually, rectally (by suppository), transdermally (in gel form), or by intramuscular injection.
Progestogens, in conjunction with the hormone prolactin, are involved in the maturation of the lobules, acini, and areola during pregnancy: mammary structures that estrogen has little to no direct effect on. However, there is no clinical evidence that progestogens enhance breast size, shape, or appearance in either trans women or cisgender women, and one study found no benefit to breast hemicircumference over estrogen alone in a small sample of trans women given both an estrogen and an oral progestogen (usually 10 milligrams/day of medroxyprogesterone acetate). However, the authors of the paper stated that the sample size was too small to make any definitive conclusions, and that further studies should be carried out to confirm whether progestogens significantly affect breast size and/or shape in trans women. As of 2014, no additional study had looked at the issue. Anecdotal evidence from trans women suggests that those who take progesterone supplements may experience more full breast development, including development beyond stage 4 on the Tanner scale (many trans women do not develop stage 5 breasts). However, there have been no formal studies with sufficiently large sample sizes to confirm this.
Progestogens alter fat distribution (e.g., by increasing fat in the buttocks and thighs), increase sex drive (only progesterone, via its active metabolite allopregnanolone; this does not occur through activation of the progesterone receptor), cause increased appetite and weight gain (only in combination with estrogen), produce a sense of calm (i.e., anxiolysis), and promote sleep (i.e., sedative and hypnotic effects).
Progesterone in particular is essential for bone health and seems to have a role in skin elasticity and nervous system function. Other effects seen with progesterone include reducing spasms and relaxing smooth muscle tone; reducing gallbladder activity; widening bronchi, which helps respiration; reducing inflammation and immune response; and normalizing blood clotting and vascular tone, zinc and copper levels, cell oxygen levels, and use of fat stores for energy. Progesterone also assists in thyroid function and bone building by osteoblasts.
High doses of progestogens exert negative feedback on the hypothalamic-pituitary-gonadal axis by activating the progesterone receptor. As a result, they have antigonadotropic properties—that is, they suppress the gonadal production of sex hormones such as androgens. As such, sufficient dosages of progestogens, such as cyproterone acetate, megestrol acetate, medroxyprogesterone acetate, hydroxyprogesterone caproate, and progesterone, can considerably lower androgen levels.
Certain progestins—including 19-nortestosterone derivatives like levonorgestrel, norgestrel, norethisterone, and norethisterone acetate, as well as, to a lesser extent, the 17-hydroxyprogesterone derivative medroxyprogesterone acetate (MPA)—have weak androgenic properties because they bind to and activate the androgen receptor similarly to testosterone, and can produce androgenic side effects such as acne, hirsutism, and increased sex drive. Conversely, certain other progestins, such as cyproterone acetate, megestrol acetate, and drospirenone, bind to and block the activation of the androgen receptor.
Androgenic progestins, such as medroxyprogesterone acetate and levonorgestrel, have been associated with an increased risk of breast cancer, which is not seen with non-androgenic progestogens such as progesterone and dydrogesterone.
Although they are not used as frequently in HRT for transgender women, dydrogesterone and hydroxyprogesterone caproate, unlike the other progestins used, are pure progestogens, and lack androgenic, glucocorticoid, or antimineralocorticoid actions and associated side effects.
The most commonly used antiandrogens for trans women are steroidal: spironolactone and cyproterone acetate. Spironolactone, which is relatively safe and inexpensive, is the most frequently used antiandrogen in the United States. Cyproterone acetate, which is unavailable in the United States, is more commonly used in the rest of the world.
Spironolactone is a potassium-sparing diuretic that is mainly used to treat low-renin hypertension, edema, hyperaldosteronism, and low potassium levels caused by other diuretics. It can cause high potassium levels (hyperkalemia) and is therefore contraindicated in people who have renal failure or already-elevated potassium levels. Spironolactone prevents the formation of androgens in the testes (though not in the adrenal glands) by inhibiting enzymes involved in androgen production. It is also an androgen receptor antagonist (that is, it prevents androgens from binding to and activating the androgen receptor).
Cyproterone acetate is a powerful antiandrogen and progestin that suppresses gonadotropin levels (which in turn reduces androgen levels), blocks androgens from binding to and activating the androgen receptor, and inhibits enzymes in the androgen biosynthesis pathway. It has been used as a means of androgen deprivation therapy to treat prostate cancer. If used long-term in dosages of 150 mg or higher, it can cause liver damage or failure.
Non-steroidal antiandrogens used in HRT for trans women include flutamide, nilutamide, and bicalutamide, all three of which are primarily used in the treatment of prostate cancer. Unlike steroidal antiandrogens such as spironolactone and cyproterone acetate, these drugs are pure androgen receptor antagonists. They do not lower androgen levels; rather, they act solely by preventing the binding of androgens to the androgen receptor. However, they do so very strongly, and are highly effective antiandrogens. Bicalutamide has improved tolerability and safety profiles relative to cyproterone acetate, as well as to flutamide and nilutamide, and has largely replaced the latter two in clinical practice for this reason. Enzalutamide is a more recently introduced non-steroidal antiandrogen with even greater potency and efficacy as an antiandrogen than bicalutamide, but it is still under patent protection and in relation to this is currently (and for the foreseeable future) extremely expensive. Moreover, enzalutamide has been found to act as a negative allosteric modulator of the GABA receptor and has been associated with central side effects such as anxiety, insomnia, and, most notably, seizures (in ~1% of patients), properties that it does not share with bicalutamide.
Non-steroidal antiandrogens may be an appealing option for those who wish to preserve sex drive and function and/or fertility, as well as for those who desire more selective action with fewer side effects than spironolactone and cyproterone acetate (which increase the risk of depressive symptoms, among other adverse effects). Bicalutamide specifically may also be a safer drug than cyproterone acetate or spironolactone, as it has a much lower risk of hepatotoxicity relative to cyproterone acetate and, unlike spironolactone, has no risk of hyperkalemia or other antimineralocorticoid-associated adverse reactions. However, bicalutamide does have a small risk of hepatotoxicity and interstitial pneumonitis.
Certain antiandrogens do not reduce testosterone or prevent its action upon tissues, but instead prevent its metabolite, dihydrotestosterone (DHT), from forming. These medications can be used when the patient has male-pattern hair loss and/or an enlarged prostate (benign prostatic hyperplasia), both of which DHT exacerbates. Two medications are currently available to prevent the creation of DHT: finasteride and dutasteride. DHT levels can be lowered up to 60–75% with the former, and up to 93–94% with the latter. These medications have also been found to be effective in the treatment of hirsutism in women.
In both sexes, the hypothalamus produces gonadotropin-releasing hormone (GnRH) to stimulate the pituitary gland to produce luteinizing hormone (LH) and follicle-stimulating hormone (FSH). This in turn cause the gonads to produce sex steroids such as androgens and estrogens. In adolescents of either sex with relevant indicators, GnRH analogues such as goserelin acetate can be used to stop undesired pubertal changes for a period without inducing any changes toward the sex with which the patient currently identifies. GnRH agonists work by initially overstimulating the pituitary gland, then rapidly desensitizing it to the effects of GnRH. After an initial surge, over a period of weeks, gonadal androgen production is greatly reduced. Conversely, GnRH antagonists act by blocking the action of GnRH in the pituitary gland.
There is considerable controversy over the earliest age at which it is clinically, morally, and legally safe to use GnRH analogues, and for how long. The sixth edition of the World Professional Association for Transgender Health's Standards of Care permit it from Tanner stage 2 but do not allow the addition of hormones until age 16, which could be five or more years later. Sex steroids have important functions in addition to their role in puberty, and some skeletal changes (such as increased height) that may be considered masculine are not hindered by GnRH analogues.
GnRH analogues are often prescribed to prevent the reactivation of testicular function when surgeons require the cessation of estrogens prior to surgery.
The high cost of GnRH analogues is a significant factor in their relative lack of use in transgender people. However, they are prescribed as standard practice in the United Kingdom.
Overall effects of HRT
Male-to-female hormone replacement therapy causes, among other changes:
- Redistribution of body fat in a feminine pattern
- Breast growth, with accompanying enlargement of the nipples
- Significantly reduced and lightened body hair
- Changes in body odor and sweat production
- Widening of the pelvis (in those who have not yet experienced epiphyseal closure)
- Reduced muscle development
- Thinning of the skin
- Less prominent veins
- Decreased libido
- Reduced gonadal size
- Ocular changes
HRT can also cause infertility, eventually leading to chemically induced aspermatogenesis. The reversibility of this effect depends on the duration of androgen-suppressing treatment. Androgen-suppressing drugs are not a substitute for other birth control methods.
The psychological effects of hormone replacement therapy are harder to define. Because HRT is usually the first physical step taken to transition, the act of beginning it has a significant psychological effect, which is difficult to distinguish from hormonally induced changes.
Characteristics unaffected by HRT
HRT does not reverse bone changes that have already been established by puberty. Consequently, it does not affect height; the length of the arms, legs, hands, and feet; or the width of the shoulders and rib cage. However, details of bone shape change throughout life, with bones becoming heavier and more deeply sculptured under the influence of androgens, and HRT does prevent such changes from progressing further.
The width of the hips is not affected in individuals for whom epiphyseal closure (fusion and closure of the ends of bones, which prevents any further lengthening) has taken place. This occurs in most people between 18 and 25 years of age. Already-established changes to the shape of the hips cannot be reversed by HRT whether epiphyseal closure has taken place or not.
Established changes to the bone structure of the face are also unaffected by HRT. A significant majority of craniofacial changes occur during adolescence. Post-adolescent growth is considerably slower and minimal by comparison. Also unaffected is the prominence of the thyroid cartilage (Adam's apple). These changes may be reversed by surgery (facial feminization surgery and tracheal shave, respectively).
During puberty, the voice deepens in pitch and becomes more resonant. These changes are permanent and are not affected by HRT. Voice therapy and/or surgery may be used instead to achieve a more female-sounding voice.
The most significant cardiovascular risk for transgender women is the pro-thrombotic effect (increased blood clotting) of estrogens. This manifests most significantly as an increased risk for thromboembolic disease: deep vein thrombosis (DVT) and pulmonary embolism, which occurs when blood clots from DVT break off and migrate to the lungs. Symptoms of DVT include pain or swelling of one leg, especially the calf. Symptoms of pulmonary embolism include chest pain, shortness of breath, fainting, and heart palpitations, sometimes without leg pain or swelling.
Deep vein thrombosis occurs more frequently in the first year of treatment with estrogens. The risk is higher with oral estrogens (particularly ethinyl estradiol and conjugated estrogens) than with injectable, transdermal, implantable, and nasal formulations. DVT risk also increases with age and in patients who smoke, so many clinicians advise using the safer estrogen formulations in smokers and patients older than 40.
Because the risks of warfarin—which is used to treat blood clots—in a relatively young and otherwise healthy population are low, while the risk of adverse physical and psychological outcomes for untreated transgender patients is high, pro-thrombotic mutations (such as factor V Leiden, antithrombin III, and protein C or S deficiency) are not absolute contraindications for hormonal therapy.
The antiandrogen bicalutamide is associated with an increased risk of heart failure when used alone (monotherapy). A study of prostate cancer patients also showed a higher rate of deaths unrelated to cancer among patients taking 150 mg/day of bicalutamide. This prompted Health Canada to withdraw its approval for 150 mg bicalutamide as monotherapy. The increased death rate has not been observed when bicalutamide is combined with a method that reduces androgen production, such as a GnRH analogue or orchiectomy. The reason for the increased rate of heart failure and death seen with bicalutamide monotherapy is not well understood.
Antiandrogens affect existing facial hair only slightly; patients may see slower growth and some reduction in density and coverage. Those who are less than a decade past puberty and/or whose race generally lacks a significant amount of facial hair may have better results. Patients taking antiandrogens tend to have better results with electrolysis and laser hair removal than those who are not. In patients in their teens or early twenties, antiandrogens prevent new facial hair from developing if testosterone levels are within the normal female range.
Body hair (on the chest, shoulders, back, abdomen, buttocks, thighs, tops of hands, and tops of feet) turns, over time, from terminal ("normal") hairs to tiny, blonde vellus hairs. Arm, perianal, and perineal hair is reduced but may not turn to vellus hair on the latter two regions (some cisgender women also have hair in these areas). Underarm hair changes slightly in texture and length, and pubic hair becomes more typically female in pattern. Lower leg hair becomes less dense. All of these changes depend to some degree on genetics.
Head hair may change slightly in texture, curl, and color. This is especially likely with hair growth from previously bald areas. Eyebrows do not change because they are not androgenic.
Some transgender women report a significant reduction in libido, depending on the dosage of antiandrogens. A small number of post-operative trans women take low doses of testosterone to boost their libido. Many pre-operative trans women wait until after reassignment surgery to begin an active sex life. Raising the dosage of estrogen or adding a progestogen raises the libido of some trans women.
Spontaneous and morning erections decrease significantly in frequency, although some patients who have had an orchiectomy still experience morning erections. Voluntary erections may or may not be possible, depending on the amount of hormones and/or antiandrogens being taken.
Testicle volume is reduced by about 25% with typical dosages and as much as 50% with higher dosages, especially after a year of HRT. This is in response to a decrease in Leydig cells, Sertoli cells, and interstitial tissue, which produce both sperm and testosterone. When testosterone is dramatically reduced, spermatogenesis is halted almost completely, and when the cells that are involved in these processes go unused, they atrophy.
The prostate and bladder shrink. The line that runs down the underside of the penis and down the middle of the scrotum—the peno-scrotal raphe, where the urogenital folds fused early in the womb—darkens. Minor water retention is likely, but spironolactone tends to counter this effect because it is a diuretic.
Childbearing, as experienced by female women, is speculative with current technology. Pre-operative sperm banking, however, can allow for the use of artificial insemination with a female partner at a later date.
Medical advances may one day make it possible for trans women to become pregnant with a donor uterus, as anti-rejection drugs do not seem to affect the fetus. The first successful uterine transplant took place in Turkey in 2011. The DNA in a donated ovum can be removed and replaced with the DNA of the receiver. In the future, stem cell biotechnology may make this possible with no need for anti-rejection drugs. However, problems may arise with the structure of the hip bones, as cisgender women generally have larger hip bones to accommodate pregnancy.
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Both estrogens and androgens are necessary in all humans for bone health. Young, healthy women produce about 10 mg of testosterone monthly, and higher bone mineral density in males is associated with higher serum estrogen. Both estrogen and testosterone help to stimulate bone formation, especially during puberty. Estrogen is the predominant sex hormone that slows bone loss, even in men.
Male-to-female hormone therapy causes the hips to rotate slightly forward because of changes in the tendons. Hip discomfort is not uncommon.
If estrogen therapy is begun prior to pelvis ossification, which occurs around the age of 25, the pelvic outlet and inlet open slightly. The femora also widen, because they are connected to the pelvis. The pelvis retains some masculine characteristics, but the end result of HRT is wider hips than a normal man, closer to those of a cisgender woman.
Skin and eye changes
The uppermost layer of skin, the stratum corneum, becomes thinner and more translucent. Spider veins may appear or be more noticeable as a result. Collagen decreases, and tactile sensation increases. The skin becomes softer, more susceptible to tearing and irritation from scratching or shaving, and slightly lighter in color because of a slight decrease in melanin.
Sebaceous gland activity (which is triggered by androgens) lessens, reducing oil production on the skin and scalp. Consequently, the skin becomes less prone to acne. It also becomes drier, and lotions or oils may be necessary. The pores become smaller because of the lower quantities of oil being produced. Many apocrine glands—a type of sweat gland—become inactive, and body odor decreases. Remaining body odor becomes less metallic, sharp, or acrid, and more sweet and musky.
As subcutaneous fat accumulates, dimpling, or cellulite, becomes more apparent on the thighs and buttocks. Stretch marks (striae distensae) may appear on the skin in these areas. Susceptibility to sunburn increases, possibly because the skin is thinner and less pigmented.
The lens of the eye changes in curvature. Because of decreased androgen levels, the meibomian glands (the sebaceous glands on the upper and lower eyelids that open up at the edges) produce less oil. Because oil prevents the tear film from evaporating, this change may cause dry eyes.
The distribution of adipose (fat) tissue changes slowly over months and years. HRT causes the body to accumulate new fat in a typically feminine pattern, including in the hips, thighs, buttocks, pubis, upper arms, and breasts. (Fat on the hips, thighs, and buttocks has a higher concentration of omega-3 fatty acids and is meant to be used for lactation.) The body begins to burn old adipose tissue in the waist, shoulders, and back, making those areas smaller.
Breast, nipple, and areolar development usually takes 4–6 years to complete, depending on genetics, and sometimes as long as 10 years. It is normal for there to be a "stall" in breast growth during transition, or for one breast to be somewhat larger than the other. Trans women on HRT often experience less breast development than cisgender women, and many seek breast augmentation; it is rare for an HRT patient to opt for breast reduction. Shoulder width and the size of the rib cage also play a role in the perceivable size of the breasts; both are usually larger in trans women, causing the breasts to appear proportionally smaller. Thus, when a trans woman opts to have breast augmentation, the implants used tend to be larger than those used by cisgender women.
In trans women on HRT, as in cisgender women during puberty, breast ducts and Cooper's ligaments develop under the influence of estrogen. Progesterone causes the milk sacs (mammary alveoli) to develop, and with the right stimuli, a trans woman may lactate. Additionally, HRT often makes the nipples more sensitive to stimulation.
Gastrointestinal and metabolic changes
Estrogens may increase the risk of gallbladder disease, especially in older and obese people. They may also increase transaminase levels, indicating liver toxicity, especially when taken in oral form.
A patient's metabolic rate may change, causing an increase or decrease in weight and energy levels, changes to sleep patterns, and temperature sensitivity. Androgen deprivation leads to slower metabolism and a loss of muscle tone. Building muscle takes more work. The addition of a progestogen may increase energy, although it may increase appetite as well.
Neurological and psychiatric changes
Mood changes, including depression, can occur with hormone replacement therapy. However, many trans women report significant mood-lifting effects as well. The risk of depressive side effects is more common in patients who take progestins. Medroxyprogesterone acetate, in particular, has been shown to cause depression in certain individuals, perhaps by affecting dopamine levels.
Estrogens can also cause prolactinomas. Milk discharge from the nipples can be a sign of elevated prolactin levels. If a prolactinoma becomes large enough, it can cause visual changes (especially decreased peripheral vision), headaches, depression or other mood changes, dizziness, nausea, vomiting, and symptoms of pituitary failure, like hypothyroidism.
Especially in the early stages of hormone replacement therapy, blood work is done frequently to assess hormone levels and liver function. The Endocrine Society recommends that patients have blood tests every three months in the first year of HRT for estradiol and testosterone, and that spironolactone, if used, be monitored every 2–3 months in the first year. The optimal ranges for estradiol and testosterone are:
|Hormone||Endocrine Society||Royal College of Psychiatry|
|Estradiol||Less than 200 pg/ml||80–140 pg/ml|
|Testosterone||Less than 55 ng/dl||"Well below normal male range"|
The optimal ranges for estrogen apply only to individuals taking bioidentical hormones (e.g., estradiol, including esters), and not to those taking synthetic or other non-bioidentical preparations (e.g., ethinyl estradiol or conjugated equine estrogens).
Doctors also recommend broader medical monitoring, including complete blood counts; tests of renal function, liver function, and lipid and glucose metabolism; and monitoring of prolactin levels, body weight, and blood pressure.
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- Wylie, Kevan; Barrett, James; Besser, Mike; Bouman, Walter; Brain, Caroline; Bridgman, Michelle; Clayton, Angela; Green, Richard; Hamilton, Mark; Hines, Melissa; Ivbijaro, Gabriel; Khoosal, Deenesh; Lawrence, Alex; Lenihan, Penny; Ivbijaro, Del; Ralph, David; Reed, Terry; Stevens, John; Terry, Tim; Thom, Ben; Thornton, Jane; Walsh, Dominic; Ward, David (2014). "Good Practice Guidelines for the Assessment and Treatment of Adults with Gender Dysphoria" (PDF). Sexual and Relationship Therapy (Taylor & Francis) 29: 35.
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- Tom Waddell Clinic Transgender Protocol - MTF and FTM clinical protocols aimed at providers
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