You guys really are sheltered, aren't you?
Here's the relevant section of the M2F hormone therapy
faq (I apologize for the lack of formatting, but it is
a lot of data. Full text can be had at:
What are hormones, and how do they work? Hormones are long-range chemical messengers of the body, manufactured and controlled by the endocrine system. Hence the title of endocrinologist for hormone doctors.
The hypothalamus produces gonadotropin-releasing hormone (GnRH). This signals the anterior pituitary gland to synthesize and release luteinizing hormone (LH). To a lesser degree, GnRH also triggers the synthesis and release of follicle stimulating hormone (FSH). Subsequently, LH and FSH signal the gonads (ovaries in females, testes in males) to synthesize and release hormones that cause differentiation of the body tissue into female or male form: estrogens, progesterones, and testosterones. A small quantity of testosterones are also produced by the adrenal gland. Proportionally, females have more estrogens and progesterones than males; males have more testosterones.
Estrogens include natural and synthetic estradiols, estrones and estriols. They excite estrogenic receptors, causing the body to differentiate into female form and function. Natural and synthetic estrogens are hereafter referred to simply as estrogens.
Progestogens (or progestins) are synthetic progesterone analogues. Progesterones and progestogens excite progesteronic receptors, which in cooperation with estrogenic activity, cause the body to further differentiate into female form and function. Natural and synthetic progesterones are hereafter referred to simply as progesterones.
Various testosterones are collectively known as androgens. They excite androgenic receptors, causing the body to differentiate into male form and function. Natural and synthetic testosterones are hereafter referred to simply as androgens.
Anti-hormones can be useful in transsexual hormone therapy because they block hormone action or production. The basic mechanisms are:
Androgen receptor antagonist: blocks the action of
androgens at certain receptor sites.
Androgen conversion inhibitor: blocks the conversion of one type of androgen to another.
GnRH agonist: Briefly overstimulates then effectively suppresses pituitary LH and FSH production. Aggressive exogenous hormone therapy indirectly reduces endogenous (natural) gonadal hormone production by fooling the pituitary into thinking that there are plenty of hormones already in the body; consequently, the pituitary reduces the LH and FSH signals that stimulate the gonads.
Postnatally administered hormones do not cause development of are opposite those born with. However, postnatal contrasexual hormone therapy does cause development of secondary sex characteristics as described below.
What are normal endogenous androgen and estrogen
The normal endogenous androgen range in a male is 300-1100 nanograms per deciliter. Estrogen is generally below 50 picograms per milliliter.
The normal endogenous androgen range in a female is 10-100 nanograms per deciliter. (within this range lower numbers are not necessarily considered better; remember, free-circulating androgens cannot bind to receptors very well, and therefore cannot cause much harm, if an androgen blocker is being used).
There are dramatic cyclic and individual variations of estrogen (estradiol + estrone) in females, with 100-400 picograms per milliliter being the most usual, with 25-700 being possible depending on the individual. 400 is considered a nominal "mid-peak" (ovulation) level. 200-250 is considered a reasonable target for exogenous estrogen treatment. Note that only natural estrogens can be meaningfully measured, so it you take any estrogen besides estradiol valerate, estradiol cypionate, or estradiol, you will not be able to accurately judge the results of a blood test.
What effect does female hormone therapy have on a
male, and how soon?
The longer after puberty hormone therapy is started, the less effective it is--but not a linear scale, e.g., results are considerably more dramatic in an 18 year old than a 28 year old, but results are not on the average dramatically different between a 38 year old and a 48 year old.
The following effects have been observed in varying degrees--anywhere from little to moderate--with extended treatment. With effective and continuous dosages, most of the changes that a particular body is genetically prone to start within 2 to 4 months, start becoming irreversible within 6 to 12 months, start leveling off somewhat within 2 years, and be mostly done within 5 years. The leveling may take longer if the testes are not removed. High levels of estrogen will cause faster development up to a point, but not better results in the long term than moderate levels of estrogen.
Fertility decreases. Sperm count drops rapidly.
Sometimes it returns to almost normal if hormonal
treatment is discontinued within the first couple of
months, but permanent sterility can occur in as little
as six months. This should not be counted on for birth
control, because a miniscule sperm count might remain
until the testes are surgically removed. Estrogens,
progesterones, and gonadal androgen production
inhibitors are the chemicals responsible for lowering
fertility. It appears to the author that the other
types of anti-androgens do not necessarily effect
fertility--but one would be wise to take frequent
fertility tests if one chooses to employ only the
other types of anti-androgens with the intent of
Male sex drive decreases. Directly stimulated erections can become infrequent and difficult to maintain. Spontaneous erections usually stop. Semen secretion decreases, usually resulting in less intense ejeculatory orgasms (however, the ability to achieve a satisfying orgasm--even with little or no semen--is determined more by psychological factors and frequent practice than anything else). The testes and prostate atrophy. The penile skin also shrinks if erections are not regularly encouraged.
Breast size increases. Typical growth is to one to two cup sizes below closely related females (mother, sisters). The growth is not always
symmetrical--neither is it for females. Sometimes the areoles and nipples swell, but generally not significantly, unless the body is less than a decade past puberty.
Fat is redistributed. The face becomes more typically female in shape. Fat tends to move away from the waist and toward the hips and buttocks.
Body hair growth (not including head, face, or pubic area) slows, becomes less dense, and may lighten in color.
Many people also report the following effects, but they are not verified in any medical literature that the author has read:
If exercise is not increased, some muscle tone is
Outer skin layer becomes thinner, lending a finer translucent appearance and increased susceptibility to scratching and bruising. Tactile sensation becomes more intense.
Oil and sweat glands become less active, resulting in dryer skin, scalp, and hair.
Scalp hair becomes thicker, and male pattern baldness generally stops advancing. In some cases, a fine fuzz may grow back along the line of where scalp hair was recently lost--but only from the living follicles, not dead ones.
Metabolism decreases. Given a caloric intake and exercise regimen consistent with pre-hormonal treatment, one tends to gain weight, lose energy, need more sleep, and become cold more easily. Sometimes the ability to concentrate is also initially diminished, but the tiredness and distraction generally pass once the body and brain become used to operating with less androgens to maintain intensity.
Fingernails become thinner and more brittle. Body odors (skin and urine) change. They become less "tangy" or "metallic" and more "sweet" or "musky". Internal emotions are amplified, becoming more apparent, distinguishable, and influential. Some people report reduced anxiety and increased sense of well-being. This could be a placebo effect. Changing the hormone therapy (adjusting dosages up or down in the regimen) sometimes causes a week or two of depression and otherwise unexplainable emotional angst.
"Female" sex drive and enjoyment increase. This observation is obviously completely subjective since males have no way to directly compare the experience. Non-ejeculatory orgasms become more likely for those with the predisposition to have them, if for no other reason than the fact that ejeculatory orgasms are difficult or impossible to achieve, and the need for sexual release forces a rewiring of perceptions and responses.
Female hormones do not:
Cause the voice to increase in pitch.
Dramatically reduce facial hair growth in most people. There are some exceptions with people who have the proper genetic predisposition and/or are less than a decade past puberty.
Change the shape or size of bone structure. However, they may change the bone density slightly.
Anybody seriously interested in gender roles and identity really ought to be looking at the transgender community. Just about all the questions have been discussed to a bloody pulp.