Testosterone Is Not Only a Men's Hormone

A patient in her early forties told me her libido had been gone for two years, her energy was flat, and she had stopped gaining anything from her training even though nothing about it had changed. She had raised it with two clinicians. Both had checked her thyroid, found it normal, and moved on.

Nobody had mentioned testosterone, because testosterone is filed in most people's minds as a men's hormone.

It is not. Women produce it every day, in smaller amounts, and it participates in libido, energy, mood, bone density, and the maintenance of muscle. When it drifts in either direction, people feel it.

Where it comes from and how much there is

Roughly half of a woman's testosterone is made directly by the ovaries and adrenal glands. The rest is converted in peripheral tissue from weaker precursors, mainly DHEA and androstenedione.

The total circulating amount is somewhere between one tenth and one twentieth of what a man carries. That sounds negligible until you remember that hormone systems work on receptor sensitivity rather than volume. Tissue tuned to a small signal responds to changes in that small signal.

Levels decline gradually with age, starting well before menopause, so a woman of forty-five often sits at around half of what she had at twenty-five. Menopause itself is a smaller inflection point than people assume, because the adrenal contribution continues. Removal of both ovaries is a different matter and drops levels sharply and immediately.

The low end

The symptoms are non-specific, which is why this gets missed. Sexual desire that has fallen from a previous baseline and is causing distress. Fatigue that sleep does not fix. Difficulty holding muscle despite consistent training. A flattening of drive that is hard to describe and easy to dismiss.

Causes worth looking for: removal of both ovaries, pituitary or adrenal insufficiency, long term glucocorticoid or opioid use, and combined oral contraceptives, which raise sex hormone binding globulin and so lower the fraction of testosterone that is biologically available.

Now the part that gets left out of most conversations, and it matters.

There is no blood level that diagnoses low testosterone in a woman. The 2019 global consensus statement, endorsed by every major menopause and endocrine society involved, is explicit: no cutoff for any measured androgen separates women with sexual dysfunction from women without it. A number below a reference range is not a diagnosis, and a number inside the range does not rule anything out.

There is a technical reason alongside the biological one. Most routine immunoassays were validated at male concentrations and become unreliable at the far lower levels found in women. Liquid chromatography with tandem mass spectrometry is the accurate method, and it is not what most labs run by default.

What treatment the evidence actually supports

I want to be careful here, because this is territory where a lot of clinics are selling more than the literature supports.

The one evidence-based indication for testosterone in women is hypoactive sexual desire disorder in postmenopausal women, diagnosed after a proper biopsychosocial assessment rather than from a lab value. In that group, at doses that produce premenopausal physiological levels, it works.

The same consensus statement found the evidence insufficient to recommend testosterone for general wellbeing, mood, cognition, bone density, muscle strength, or body composition. Those are precisely the promises attached to it most often.

It also advises against the delivery methods that are marketed hardest. Pellets and injections produce supraphysiological levels. Oral testosterone harms lipids. Compounded preparations are a last resort where no approved product exists, which is the situation in the United States, since there is no female-dose testosterone approved by the FDA. In practice that means carefully dosed-down male transdermal products, prescribed off-label, with real monitoring: a baseline level, a recheck at three to six weeks, then every six months, watching for acne, hair changes, and voice deepening. If nothing has improved by six months, it stops.

The high end

This is the more common presentation in my clinic and the easier one to measure.

Excess androgen shows up as hair growth on the face, chest, or abdomen, acne along the jawline and chin, thinning at the crown, and irregular or absent cycles. Polycystic ovary syndrome accounts for most of it, and the mechanism runs through insulin: high insulin drives ovarian androgen production and suppresses SHBG at the same time, which raises free testosterone even when the total looks unremarkable.

That is why SHBG belongs on the panel. It is the value that explains the mismatch between a normal total testosterone and a woman with obvious clinical androgen excess.

Other causes deserve exclusion before the PCOS label is applied: non-classical congenital adrenal hyperplasia, which is checked with a morning 17-hydroxyprogesterone, along with thyroid disease and elevated prolactin.

One pattern needs urgent attention rather than a routine workup. Symptoms that appear suddenly and progress over months, particularly with voice deepening, clitoral enlargement, or male pattern balding, and a total testosterone well above the usual female range, raise the question of an androgen-secreting tumor of the ovary or adrenal gland. It is uncommon. It is also the reason speed of onset is a question I always ask.

How to have the conversation

If this sounds like you, ask for the panel rather than the single number: total testosterone measured by mass spectrometry, SHBG, calculated free testosterone, DHEA-S, and 17-hydroxyprogesterone, drawn in the morning and, if you are still cycling, in the first week or so of your cycle.

Then read it with someone who treats the result as one input rather than the whole answer. High testosterone is measurable and treatable. Low testosterone is measurable too, and what to do about it is a narrower conversation than the internet suggests.

Either way it is a real hormone doing real work in a woman's body, and it is worth asking about.

This article is for educational and is not individual medical advice. Testosterone testing and any decision about therapy should be managed with a physician who knows your full history.