Testosterone and Women
Testosterone isn’t just a ‘male’ hormone. It has around 200 known functions in healthy women, many of which are comparable to those in healthy men, and most of which are still poorly understood. One of those is enabling sexual desire and arousal. The scientific picture is still hazy, and the FDA has yet to approve any prescription testosterone medications for women. But there is a general consensus that for some women with low sex drive or arousal, and for some with chronic fatigue, low doses of supplemental testosterone mean a low chance of side effects, and a fairly high chance of improvement.
Testosterone is associated with men for a reason, but it would be misleading to say that women produce “low” amounts of it. Better to say that men produce very high amounts – ten times higher than women on average. For perspective, women finishing puberty have the highest blood concentration of estrogens (a family of hormones with multiple members), but they still have ten times as much testosterone. It is their most abundant hormone.
Like estrogens, testosterone is synthesized in fat cells, special glands, and ovaries, but unlike them, menopause has little impact on testosterone levels. Starting around age 20 a woman’s testosterone levels begin a slow but steady decline. The extent to which this hinders the hormone in its normal jobs – spiking before and after sex, arousing the vagina, increasing with romantic infatuation, enhancing orgasm – is hotly debated. Indeed, a room temperature debate is hard to imagine.
Testosterone Depletion Can Lead to Sickness
By the time most women reach menopause, their testosterone levels have declined by half. This is not always a bad thing, and some women are asymptomatic with even larger reductions.
Others are not so lucky. Some of menopause’s most unpleasant symptoms, traditionally blamed on low estrogen, are now thought to come from low testosterone, especially in cases where supplemental estrogen fails to help. Mood swings, fatigue, “mental fogginess,” weight gain, fragile bones, and loss of libido are just a few. All are more likely when an operation removes the ovaries, and thereby eliminates the richest source of reproductive hormones, rushing the patient into menopause whatever her age. An untold number of other conditions can also cause the symptoms, including disorders of the pituitary or adrenal glands. Some women experience a loss of sex drive without any other abnormalities. This mysterious condition will sometimes respond favorably to testosterone therapy even if testosterone levels were normal to begin with.
Further complicating matters, testosterone levels in women show regular but wide fluctuation, which makes them hard to measure. Most doctors instead rely on symptoms when determining the need for testosterone therapy. When a loss of sexual desire, sexual arousal, or mental alertness significantly affects a woman’s life and relationships, and has not improved with supplemental estrogen, many doctors give testosterone a try.
The Solution for women and testosterone?
To date there are no prescription testosterone supplements for women in the US, but healthcare workers are free to order off-label preparations on a case-by-case basis. These preparations are taken in a variety of ways, from pills to patches to creams, and even as tablets that are inserted under the skin to slowly release their contents. Many researchers think pills are best, since oral medications alone have to pass through the liver on the way to the bloodstream, and since some drugs must be chemically modified in the liver for full effect. Other researchers recommend artificially synthesized testosterone, testosterone from specific natural sources, and even methyltestosterone, a close relative of the testosterone molecule that might enter the bloodstream more efficiently.
Virtually all agree that testosterone preparations for women should begin at much lower doses than for men, where their therapeutic value seems to max out without harmful or masculinizing side-effects. They also agree that not only should testosterone be tried after estrogens have failed, but that it should always be taken with estrogens. Solo testosterone therapy is uncharted terrain, where an absence of major side effects has yet to be shown. And what little research there is suggests an inverse relationship between sexual arousal and testosterone levels when estrogens are low.
When estrogens are given with testosterone as recommended, this relationship reverses itself, with weak but measurable increases in sexual desire, and slightly stronger increases in arousal, orgasm quality, and mental focus. Other menopausal symptoms may be relieved in the process, though the evidence is too weak for testosterone to be given for those symptoms alone.
There are, of course, reasons for exercising caution with testosterone therapy have nothing to do with gender norms. The emerging link between birth control pills and breast cancer has made millions of women skittish about all supplemental hormones. While there are no guarantees in medicine, current studies suggest that elevated estrogens are the culprit for breast and cervical cancer, whether they are elevated because of birth control or another hormone therapy. Supplemental estrogens in testosterone therapy involve smaller doses than in birth control, so it might be tempting to conclude that testosterone therapy is off the hook. Not so fast: testosterone can be chemically modified in the body to become estradiol (an estrogen). This means that higher testosterone levels can, in theory, lead to higher estradiol levels – a fact that may account for certain therapeutic benefits, while also opening the door to cancer risk.
Happily, there are ways to close the door, if not to shut it completely. Testosterone is converted to estradiol by an enzyme called aromatase, which creates a molecular ring structure whose derivatives often smell sweet. A drug called anastrozole can be used to disable aromatase molecules, blocking the only known pipeline between testosterone and estradiol, and helping to ensure that most estradiol is from the medication pipeline. This dramatically lowers the odds that estrogens will rise to cancer-causing levels during testosterone therapy. So promising is this testosterone-estrogens-aromatase combo that it is sometimes used to treat hormonal imbalances in breast cancer survivors, where it less likely than other medications to cause dangerous blood clotting.
Some risks, unfortunately, must be accepted as part of the package, and for certain women they are serious enough to rule out the package completely. Testosterone therapy may lower “good” cholesterol (LDL), making it an unsafe option for women who already have heart disease or a poor cholesterol profile. Despite the benefits of anastrozole, most doctors won’t recommend supplemental testosterone to women with breast or uterine cancer, or who have recovered from either. Since the liver plays a role in processing and detoxifying all drugs, women with liver disease should avoid testosterone supplements. Finally, women who take testosterone while pregnant may prompt a sensitive female fetus to develop hermaphroditic genitals and other unfeminine traits.
For countless women, testosterone therapy is a way to better health and a better life. But it is rarely the only way, and should never be taken before a thorough and honest discussion with a qualified physician. Few physicians are more qualified than Dr. Joseph Olivieri, MD, FAAFP, who has over 40 years of experience and routinely does endocrinology work with Ageonics Medical. Dr. Olivieri was a Staff Virology Physician at NYU Medical Center and the HIV Medical Director at the Greenwich House. Call 215-510-7020 or email email@example.com to schedule a free consultation.