Testosterone has been described as the hormone of desire… Although it's in the androgen hormone class, considered to be “male” hormone, both men and women produce testosterone. It's the difference in amounts produced and the balance between estrogen and testosterone that determine male or female body characteristics.
Interestingly, many more articles have been written about overproduction of testosterone in women, as can occur in polycystic ovary syndrome, for example. Underproduction can also be a problem for women, but doctors rarely test for this.
With low testosterone, women can feel fatigued and notice less interest, not only in sex, but in doing things they normally like to do. The term “lack of a sense of wellbeing” has been used to describe how women with low testosterone can feel.
Physically, they may notice decreased muscle size and strength, and reduced hair growth on the body, particularly underarm, pubic and leg hair. These physical changes often carry more weight when speaking with your healthcare provider about the potential for this type of hormone imbalance.
Interestingly, taking hormones by mouth can lead to low testosterone effect. The liver filters virtually everything you swallow as soon as it is absorbed from your digestive system. This is referred to as the “first pass effect”, where the drug is changed or partially removed from the blood stream before it has a chance to reach the rest of the body. This is one reason that transdermal drugs (or drugs administered through the skin) are generally used in lower doses. With the transdermal route, the drug reaches the body before the liver has a chance to metabolize it. Hormone preparations are generally 1/10th the dose when given through the skin, as compared to dosing by mouth.
However, with oral hormones there is another known effect… In response to swallowed hormones, the liver produces a special protein, called sex hormone binding globulin (SHBG) that binds to hormones making them unavailable to act in the body and, essentially, inactive.
When estrogen is swallowed, such as with hormone replacement or birth control tablets, the liver is stimulated to produce SHBG, presumably a mechanism developed to protect us from accidentally ingested hormones in our food.
However, SHBG binds testosterone 10 times more strongly than estrogen. This means that taking estrogen by mouth will result in increased SHBG that will scoop up much of the testosterone your body is producing. Testosterone is still being produced but you may experience the symptoms of low testosterone. Regular blood tests for total testosterone would show a normal amount, but a test for “free testosterone” (testosterone not bound to proteins) would show the effective deficiency.
So, what can be done to correct testosterone deficiency? I always recommend treating the cause if one is identified so, for women with a secondary deficiency caused by taking estrogen by mouth, a simple solution is to change the estrogen to a patch, cream or gel formulation, eliminating the first pass effect on the liver and reducing production of SHBG.
If this is not the cause, and total serum testosterone is found to be low, testosterone replacement can be considered. Swallowed testosterone is known to be hard on the liver, with increased liver cancer reported with some oral forms. As well, available tablets and capsules currently on the market are dosed for men and contain far more hormone than women need. I’ve seen prescriptions for women to take one man-sized 40mg capsule once or twice a week, but even this is more than women would produce, and would result in swings in testosterone blood levels that would be far too high on the days immediately after taking a dose.
Women produce less than 1mg of testosterone daily. It is easy to understand that a 40mg capsule would come with the recommendation to stop taking it if she developed facial hair growth or acne. Even the cream formulas that are available come in 25 and 50mg pouches or pumps with no accurate way to measure a lower amount.
However, testosterone cream can be accurately compounded by a pharmacist and loaded into needle-free syringes for accurate measurement. I always prepared the cream as 1% testosterone (10mg/ml) making it easy to calculate the desired dose. A 1ml syringe would contain 10mg – generally enough for 10 days of testosterone replacement, although some women have reported results with doses as low as 0.15mg!
Because hormones are stored away in fatty tissues in the body, I generally recommended using 2mg daily for the first week or two (since some of this would be stored away) then reducing to 1mg or less daily to avoid any chance of overdosing. One of the first signs of too much testosterone is often an outbreak of acne. I encourage women to identify the lowest dose that is effective for them – the “normal” amount can vary from person to person, and we need to remember that we are adding to the amount being produced, which can also vary from person to person.
Men can also become deficient in testosterone. Some refer to this as “andropause”… others have jokingly called it “grumpy old man syndrome” since deficiency most commonly occurs later in life, the man may be stooped and thin due to decreased muscle and possibly the onset of osteoporosis, and his mood may have become less than cheery.
Testosterone replacement for men is readily available in capsules, injections and creams and, although somewhat less convenient, the creams or injections would be preferred to reduce the effect of hormone on the liver. However, as injections are generally given every 2 to 4 weeks, they have the disadvantage of producing a higher blood level of hormone immediately after the injection and a lower level before the next injection is scheduled. A simple blood test would confirm that testosterone is needed and that the dosing is correct.
So, if any of the symptoms of low testosterone sound familiar, talk to your doctor about it. If you are interested in more information, I would recommend “The Hormone of Desire” by Dr. Susan Rako as an excellent source of information on testosterone deficiency in women.
