What You Need to Know About Testosterone for Women

By Marie Savard MD

Editor’s Note: Following the June 4th FDA hearing about the controversial female libido pill, flibanserin, ThirdAge posted an article called “What You Really Need to Know About Pink Viagra”. In that article, we promised to post an article explaining the role of testosterone in the female sex drive. Here it is: 

Testosterone is a male hormone, but women’s adrenal glands and ovaries naturally produce some as well. In addition to playing a key role in our libido, testosterone is important for the health of many organs including bones, muscles, and even the brain. Yet our levels of testosterone decline by more than half between the ages of twenty and forty and continue to decline as we get older. Fortunately however, even when surgical removal of the ovaries robs a woman of 50 percent of what is left of her testosterone, fat cells take over to some extent just as they do for every woman. Yet for many of us, the fat cells don’t supply all the testosterone we need. That’s when replacement therapy is recommended.

The catch, though, is that science hasn’t come up with a totally reliable test to determine the level of testosterone each of us requires to maintain a healthy sex drive and good health in general. To complicate things, many of the tissues of a woman’s body, including the brain, convert testosterone into estrogen—a process known as aromatization. So is the problem really about too little estrogen and not a testosterone issue? That’s a tough one, but some women who are given plenty of estrogen replacement after surgical menopause still don’t feel right until a bit of testosterone is added to the mix.

Since there are no reliable blood tests to check for testosterone levels in women, simply measuring testosterone is not good enough. In most women, including women with reduced libido, the testosterone levels will show up in the normal range. But this doesn’t mean there isn’t a problem. Also, a big myth out there is the notion that a hair, blood, saliva, or other analysis can reliably test for testosterone. That’s not true.

Even the international panel of experts that convened in the United States had a hard time coming up with a precise definition of testosterone insufficiency or defining how to know if a woman has insufficient testosterone. However, they suggest three basic criteria:

1. Symptoms of low testosterone should be present: unexplained fatigue, sexual function changes such as reduced libido (meaning reduced interest and pleasure in sex) and reduced sense of well-being (meaning “not feeling like your old self”).
2. Because adequate estrogen is also critical to our sense of well- being and sexual function, estrogen “status” should be acceptable, meaning if you are postmenopausal with low estrogen symptoms, you should first be treated with estrogen to see how you feel before getting a diagnosis of a low testosterone problem.

3. So-called “free testosterone” blood test results should be low, that is below or at the lowest premenopausal testosterone levels. (This is not very satisfying since, as I’ve already stated, the blood tests are unreliable. I guess if your levels are high, it is probably true you won’t benefit from testosterone therapy, but otherwise I am not sure how meaningful blood tests are.)

The experts came up with a series of questions for doctors that can help them home in on whether you may have a problem that could benefit from testosterone therapy. Be warned, however, that there is no great body of data regarding safety and long-term effects or the best way to give testosterone to women. Yet I wanted to give you as much information as possible. Here is my version of the questions doctors are supposed to ask women. Why shouldn’t you read them for yourself?

• Do you have symptoms that are typical of low testosterone, such as low libido, decreased energy, and a general sense of not feeling well?
• Is there another possible reason for these symptoms such as anemia, low thyroid, depression, or another condition? If so, get a checkup and start treatment for the other condition(s) first and see what, if any, symptoms remain.
• Is your estrogen situation okay? In other words, if you are postmenopausal with hot flashes and/or other low estrogen symptoms, or have had a hysterectomy with ovaries removed, have you tried a low dose of estrogen first to find out if that is sufficient to make you feel better?
• Did you have blood testing for testosterone? Is your level low (less than 20 ng/dl or, after ovaries removed as low as less than 10 ng/d)? Although blood tests are not always helpful, a low to low-normal result may help confirm that your symptoms could be due to low testosterone.

• Did you have blood testing for sex hormone binding globulin (SHBG)?
• Are you taking oral estrogen or oral contraceptives? Oral (not transdermal, such as the patch or vaginal) estrogen can increase your sex binding proteins so your total testosterone level could be falsely elevated or normal when in fact the amount of “free” active testosterone traveling around to do its job is actually low.

Women have been prescribed testosterone treatment for over sixty years. A synthetic testosterone called methyltestosterone was first given to women to treat their libidos and “sense of well-being.” Back then the treatment was oral, but today hormone pellets or implants, skin patches or gel, are available in addition to oral forms of testosterone added to an estrogen regimen. (Testosterone is usually not taken by itself, but together with estrogen.) Research studies have shown that symptoms of reduced libido and generally feeling less than well can be helped by testosterone. Patches of testosterone at doses of 150–300 ug/day (along with oral estrogen) have been effective but are not currently FDA-approved for use in women. The combination of oral estrogen and oral methyltestosterone at a dose of 1.25 to 2.5 mg apparently also worked in another recent study, and this combination has been around for a number of years. It is the only available prescription treatment for women in the United States. Because there are no long-term randomized controlled studies, judging its effectiveness—not to mention its safety—is difficult.

However, a British study published in the New England Journal of Medicine in 2008 reported that a testosterone patch can boost libido in postmenopausal women. Of the 814 participants with low sexual desire, some got 300 micrograms of testosterone every day, a second group got 150 micrograms of testosterone per day, and a control group got a placebo. The women who received the higher dose of testosterone reported having good sex two or more times a month while the placebo group had sex less than once a month. Women on the lower-dose patch said they had increased desire but the number of times they had sex didn’t change. The downside, though, is that the women on the high dose of testosterone were more likely to report the growth of facial and body hair, loss of hair on the head, and lowered voices. Also, four cases of breast cancer were diagnosed among women taking testosterone compared with none among the placebo group but one of the women with breast cancer appeared to have had the disease before she started the study.

For the record, I always resist prescribing oral testosterone because I’m afraid there will be too many androgenic (male) side effects, such as lowering of good cholesterol, raising red blood count, adverse effects to the liver, and the appearance of male characteristics such as hair growth on the face and body and a low voice.

While the injectable form of testosterone is occasionally prescribed, I think it gives levels of the hormone that are too high and too unpredictable. Some women prefer pellets of testosterone injected. They last four to six months.

I am not recommending any specific testosterone regimen. However, if I were to prescribe anything, I would opt for the transdermal (meaning “through the skin”) cream or patch and not an injectable and definitely not an oral one that must pass through the liver—meaning that there would be a greater effect on the liver as well as the need for a higher dose. For men, there is a commercially available testosterone gel and also an “under the tongue” pill. However, no such ready-made products are available yet for women. (One would think science would be much more advanced when it comes to testosterone treatment in women since one-third of women have a hysterectomy and all of us will go through menopause at some point.)

What’s the difference between Free and Total Testosterone?

Hormones travel in the blood aboard “trains” that move them from place to place in the body. The trains are special proteins. Those called sex binding globulins are like boxcars that carry hormones rapidly from here to there. If all the testosterone in the body is on the train (that is, attached to the sex binding globulins), none is “free,” meaning off the train and able to do its work. When the testosterone is riding the train, it’s not performing any function in the body.

Using hormones, whether for menopausal symptoms or birth control, increases the number of “boxcars” available for testosterone, so whatever testosterone you have hops onboard, leaving none free to circulate on its own and do its job. Consequently the total testosterone level in the body may be high, but it’s all taking a trip on the train rather than reporting to work.

This is why many women need to reduce rather than raise estrogen dosages and/or take a small amount of testosterone with the estrogen if libido is a big issue. What’s also interesting is that as more women continue to take low-dose birth control pills up until the time of menopause (to control bleeding and to treat perimenopause symptoms as well as prevent pregnancy) they have no clue that the Pill could diminish their libido and that this could last for some time even after they stop taking the Pill.

However, while menopause may dampen your desire somewhat due to reduced hormone production, it does not necessarily mean the end of your sex life.