There are always a lot of questions about testosterone, more so now, it seems, because of social media. I see testosterone disinformation daily from a rogue’s gallery of doctors, scientists, hormone companies, podcasters, trainers, and celebrities. Testosterone is promoted for mood, muscles, brain health, bone health…you name it. The latest one that made me do a massive double-take was testosterone for dry eyes in menopause. I mean, no.
If you only got your information from social media, you couldn’t be faulted for thinking that testosterone cures everything, is the veritable fountain of youth, and is also an admission ticket to a super secret cool girls club. And yet, no menopause or endocrine society recommends testosterone outside of treatment for libido-related concerns. I will be addressing libido in another post. This post is about everything but libido.
A Primer on Testosterone
Androgens are a class of reproductive hormones traditionally associated with male characteristics, although since they were discovered, we now know they are not exclusively male hormones. The androgen that typically leaps into everyone’s mind is testosterone, but other important androgens you may or may not have heard of are dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), androstenedione, and dihydrotestosterone. DHEA and androstenedione are prohormones, meaning they don’t do much on their own; their job is to be converted into other hormones that can affect the body. Testosterone is both a hormone, meaning it directly affects the body, and also a prohormone, as it is converted into dihydrotestosterone (another androgen) or estradiol (an estrogen). To review testosterone's impact, we don’t need to get into these details, so we’ll proceed by discussing testosterone in general, understanding that its impact on the body could be via one of these three mechanisms.
Sources of Testosterone
There are three sources of testosterone for women: the ovaries, the adrenal glands, and the peripheral tissues, such as bone, muscle, and fat. The peripheral tissues convert precursor hormones into testosterone but don’t make the precursor hormones themselves.
The adrenal glands contribute about 50% to the testosterone pool by making testosterone directly or by making the precursor hormones dehydroepiandrosterone sulfate or DHEAS, DHEA, and androstenedione, which are then converted into testosterone.
The ovaries contribute to the other 50% of the testosterone in the pool. Some testosterone is produced directly by the follicles (developing eggs), but the ovarian tissue also makes androstenedione and DHEA, which can then be converted into testosterone.
Testosterone levels are highest when you are in your 20s, and from then on, they gradually decrease. There is no sharp drop in testosterone around menopause; all decreases are age-related. (I am acutely aware that this conflicts with the marketing messages from the menopause testosterone lobby, but facts, as they say, are facts). One study suggests there is actually a slight uptick in testosterone levels when women are in their 70s. When the ovaries are removed, testosterone levels drop by about 50%.
How is this possible? Shouldn’t testosterone levels drop with menopause if the follicles stop producing hormones? It is true that the follicles (eggs) produce some testosterone. However, the ovarian tissue (the part of the ovary that physically supports the follicles) still produces the prohormones that are converted into testosterone.
In one study, researchers measured hormone levels from over 1,400 women aged 18 to 75. The steepest drop in testosterone (although not a sharp cliff) was in the early reproductive years (between ages 18-24 and ages 25-34), and no menopause-related decrease was seen. Another excellent paper followed hundreds of women over seven years, before and after their final menstrual periods (FMP), and concluded that testosterone levels did not change related to the final menstrual period. Testosterone levels remained stable for several years before and after menopause. So, we can be quite certain that menopause is not a sentinel event as far as testosterone is concerned.
Most testosterone (66% or so) is tightly bound to a protein called sex hormone–binding globulin (SHBG), which is like a short-term storage facility. Some testosterone (33%) is loosely bound to albumin, another protein, and about 1% is freely circulating; this is called free testosterone (original, I know). We used to think that only free testosterone could affect the tissues, but that concept has been challenged.
And there is one more thing that makes studying testosterone challenging. Testosterone has a significant intracrinology; it can be made inside a cell and then broken down inside it. This means a cell can see a significant effect from testosterone, yet the blood levels don’t budge.
Testosterone Testing
Measuring testosterone levels in women is challenging as the tests are not good at accurately recording the lower levels typically seen in women. The available tests were direct assays for a long time, but these are unreliable in the female range. Other methods of testing testosterone are liquid/gas chromatography and tandem mass spectrometry, which are considered accurate but, until recently, weren’t readily available. The latter tests, liquid/gas chromatography, and tandem mass spectrometry, are recommended. Many studies use direct assays, which often limits their relevance.
The current recommendation for women is to use total testosterone levels obtained via liquid/gas chromatography or tandem mass spectrometry. The total testosterone level includes all the bound and free testosterone. This recommendation is from the 2019 Global Consensus Position Statement on the Use of Testosterone Therapy for Women, which is endorsed by all the major menopause and endocrine societies around the world. This is because measuring free testosterone isn’t easy, and we don’t have good data on how to apply free testosterone levels meaningfully.
Who Should Get Their Testosterone Level Checked?
Checking testosterone levels for women is only recommended for two reasons: