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By Dr J Kabyemela, MD

It is estimated that up to 15% of women are affected by the distressing condition of hirsutism or excessive body hair. In the vast majority of cases, there is an underlying hormonal (endocrine) problem, the biggest culprit being polycystic ovarian syndrome (PCOS).

The most important hormones determining distribution and thickness of hair are the androgens, also loosely called ‘male sex hormones’. This latter term is not strictly correct as women do normally produced androgens even though it is not to the levels seen in men. In conditions such as Polycystic Ovarian Syndrome (PCOS), the level of active androgens in circulation tends to be higher than the normal female physiological range.

The influence of androgens on hair growth varies depending on the part of the body. For instance, growth of eyelashes or even eyebrow hair is not at all dependent on androgens. On the other hand, hair growth on the chest, upper thighs, lower abdomen and the back is heavily dependent on androgens. Normal levels of active androgens in women will not support significant hair growth in these parts of a female anatomy. Its presence is therefore always regarded to be abnormal. Approximately 4 out of five women with this kind of hair growth will be found to have some degree of polycystic ovarian syndrome (PCOS), a condition that is discussed separately and in more detail here:

Why excessive hair

Women with polycystic ovaries tend to have resistance to the hormone insulin. Insulin is primarily a utility for regulating carbohydrate metabolism in the body. Because of the resistance, levels of insulin produced (by the pancreas) are increased. Insulin does have the direct effect of making ovaries produce more androgens.

There is also an indirect effect: Normally androgens are bound to a protein aptly called ‘sex hormone binding protein’ or SHBG. When the androgen is bound, it is inactive. It is only the proportion that is free (unbound) that is available to have physiological effect such as stimulation of hair growth. This means, when there is low level of the binding protein, more of the androgen is available to roam free. Insulin, levels of which are raised in PCOS, has the effect of suppressing production of the sex hormone binding protein by the liver.

Other causes of excessive androgen and hirsutism

Some tumours  arising from the ovaries or adrenal glands do produce high levels of androgens. Typically in women affected by these, the onset of excessive hair growth is rather rapid and they may display other features such as central obesity (cushingoid obesity). Some of these tumours could be malignant so rapid correct diagnosis is essential. These tumours account for about 0.1 – 0.3% of hirsutism cases. They are therefore rare.

Cushing’s Syndrome: This is a condition where there is excessive production of the steroid cortisol. One of the features of Cushing’s syndrome could be male-type facial hair growth. Other features such as central obesity are more prominent in Cushing’s.

Congenital adrenal hyperplasia (CAH): This is an inherited condition which presents in various forms. The majority of cases of classic congenital adrenal hyperplasia (CAH) present early in infancy with features such as severe vomiting and resultant dehydration. The underlying problem is deficiency of an important enzyme called  21-hydroxylase. This is responsible for cortisol production by the adrenal glands.  When the enzyme deficiency is moderate, presentation is in childhood typically with precocious puberty. The form of congenital adrenal hyperplasia (CAH) associated with hirsutism in young women is known as Non-classic CAH. Here, the deficiency of the enzyme is mild and may only be recognised because of the virilising effects such as hirsutism. Mode of inheritance is autosomal recessive. This means, the individual needs to inherit the gene defect from both parents to have the condition.

Acanthosis nigricans: This is a condition the features of which are mostly caused by severe insulin resistance. This creates a situation where insulin production is rumped up significantly. Excessive insulin in the body will have the effects described above whereby circulating active androgen levels are high with resulting hirsutism.

Drugs: Some androgenic drugs such as testosterone or anabolic steroids, when taken over a prolonged period of time, can have virilising effects including excessive body hair growth. Other drugs which are not androgenic but which could have that effect on body hair include Phenytoin (an anti-convulsant), Psoralen (used for psoriasis), Minoxidil (initially used to treat high blood pressure, now largely used to treat male baldness), Penicillamine (used in Rheumatoid arthritis) etc.

Idiopathic hirsutism: Around 6% (1 in 16) of women with excessive body hair are found not to have any identifiable causative factor.

Management of female excessive body hair (hirsutism)

A doctor seeing a woman with this problem needs to take a careful detailed history, including family history. This will help give pointers to possible causes. This will be followed by a physical examination.

Investigations, which tend to include various hormone assays, will depend on the suspected underlying cause garnered from the history and examination. This is important because timing of the test may be crucial in reaching the correct diagnosis. For instance, in suspected Non-classic congenital adrenal hyperplasia (discussed above), raised 7-hydroxyprogesterone is diagnostic but this needs to be checked in an early morning sample. Overall, free androgen index is regarded as the most sensitive test to diagnose elevated androgen activity of whatever origin.

Pelvic and abdominal ultrasound scan will help in the diagnosis of conditions such as polycystic ovaries or adrenal tumours.

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Excessive body hair (hirsutism) in women