Excess of male hormones in female body (hyperandrogenism) is common endocrine disorder present in some 10% women of reproductive age. It is defined biochemically as elevation of any of the serum male hormones (androgens): testosterone, androstenedione or dehydroepiandrosterone sulphate (DHEA-S). The clinical expression of androgen excess is hirsutism and in more severe cases virilisation.
Hirsutism represents the presence in females of pigmented thick terminal hair in a typical male distribution i.e. in the so-called androgen sensitive areas (the upper lip, chin, sideburns, chest, lower abdomen, intergluetal area and thights). Clinical signs of virilisation in addition to hirsutism include temporal baldness, enlargement of clitoris, deepening of the voice, development of a male muscular pattern and body habitus, atrophy of the breasts, irregular periods and psychological changes such as increased libido and aggressive behaviour. Hirsutism may sometimes be accompanied by androgenic alopecia, which is an androgen-dependent thinning of scalp hair.
Skin is a target tissue for androgen hormone action. Male hormones regulate the development, growth and activity of the pilosebaceous unit, which consists of the sebaceous gland and hair follicle. The ability of testosterone to exert androgen effects in skin is dependent upon its ability to bind to intracellular androgen receptors and on its conversion to more potent hormones - DHT.
However, there appears to be a poor correlation between serum testosterone concentrations and the degree of hirsutism in hirsute women. Testosterone and DHT, the most potent circulatory androgens, are highly bound in serum to sex hormones binding globulin (SHBG) and albumin, leaving only a small "free" biologically active fraction. In women only about one percent of circulating testosterone is normally “free”, 66 per cent is bound to SHBG and 30 per cent to albumin. Small changes in SHBG have profound effects on “free” testosterone. Because SHBG levels are lower in hyperandrogenism and obesity, circulating “free” testosterone can be elevated in women with normal total testosterone levels and this could account in part for hirsutism in these conditions.