Hirsutism is caused by an excess production of androgens {6}. Androgens are hormones in our body, which are responsible for distribution of body hair and are also responsible for the rate of hair growth. They facilitate the transformation of vellus to terminal hairs in androgen-sensitive areas, including: non-sexual, ambosexual and sexual areas.
Non-sexual skin areas are typically independent of the effect of androgens, and include eyelashes, eyebrows, lateral and occipital aspects of the scalp.
Ambosexual skin areas, for example, lower pubic triangle and axillae, are quite sensitive to androgens. Minimal increases of adrenal androgens observed in early puberty are sufficient for the development of terminal hair in these areas.
Sexual skin areas respond only to high concentrations of androgens. These areas include the face, chin, chest, lower abdomen, lower back upper thighs, upper arms, and upper pelvic triangle. Terminal hairs in these areas are typically masculine, but in females constitute hirsutism.
Severe hirsutism is usually caused by high level of androgen, which can be brought about by a number of medical conditions. These include:
1. Idiopathic Hirsutism is the most common form of hirsutism, where the cause of excessive hair growth is unknown. This form of hirsutism is thought to be hereditary and as such, there would be a family history of the condition. Women who suffer from idiopathic hirsutism typically have no other symptoms associated with other forms of hirsutism apart from excessive hair growth.
2. Polycystic ovary syndrome (PCOS) , a common condition caused by an imbalance in sex hormones, causing irregular periods, infertility, obesity, and oftentimes multiple cysts on the ovaries. PCOS is known to be the most common identifiable cause of hirsutism and is present in about 70 to 80% of women suffering from hirsutism {1, 7}.
3. Late-onset congenital adrenal hyperplasia , which is an inherited condition involving an abnormal production of steroid hormones, such as androgen and cortisol, and is an underlying cause of hirsutism in 2-5% of women with hirsutism.
4. Cushing's syndrome , which occurs when the body is exposed to an excess of cortisol over a long period of time. Cortisol is a steroid hormone, involved in the body's response to stress. An increase in cortisol levels disrupts the balance of sex hormones in the body; this can lead to hirsutism {7}.
5. Tumours , particularly androgen secreting tumours of the ovary or adrenal, although these rarely cause hirsutism {8}.
6. Medications , such as danazol, used in the treatment of women with endometriosis, can cause hirsutism in susceptible individuals {7, 8}.