Causes
Hirsutism can be caused by either an increased level of androgens, the male hormones, or an oversensitivity of hair follicles to androgens. Male hormones such as testosterone stimulate hair growth, increase size and intensify the growth and pigmentation of hair. Other symptoms associated with a high level of male hormones include acne, deepening of the voice, and increased muscle mass.
Growing evidence implicates high circulating levels of insulin in women for the development of hirsutism. This theory is speculated to be consistent with the observation that obese (and thus presumably insulin resistant hyperinsulinemic) women are at high risk of becoming hirsute. Further, treatments that lower insulin levels will lead to a reduction in hirsutism.
It is speculated that insulin, at high enough concentration, stimulates the ovarian theca cells to produce androgens. There may also be an effect of high levels of insulin to activate the insulin-like growth factor-I (IGF-1) receptor in those same cells. Again, the result is increased androgen production.
Signs that are suggestive of an androgen-secreting tumor in a patient with hirsutism is rapid onset, virilization and palpable abdominal mass.
The following may be some of the conditions that may increase a woman's normally low level of male hormones:
- Polycystic ovary syndrome, abbreviated PCOS, (the most common)
- Congenital adrenal hyperplasia, in turn mostly caused by 21-α hydroxylase deficiency
- Cushing's disease
- Growth hormone excess (Acromegaly)
- Tumors in the ovaries
- adrenal gland (cancer), Von Hippel-Lindau
- Certain medications
- Insulin resistance
- Stromal Hyperthecosis - in postmenopausal women
- Obesity: As there is peripheral conversion of androgens to estrogen in these patients, this is the same mechanism as polycystic ovary syndrome, PCOS.
- Use of drugs like Tetrahydrogestrinone
- Adverse effect of Phenytoin
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