Definition of hirsutism

Hirsutism is a common disorder, which affects up to 10% of women between the age of 18 and 45 years.

It is defined as the presence of excessive terminal hair in androgen-dependent areas of a woman´s body. It has to be differentiated from hypertrichosis, which is usually familial in nature and associated with an endocrine dysfunction  - such as thyroid dysfunction - or with medications such as phenytoin or minoxidil.

Hypertrichosis is excessive growth of thin vellus (nonpigmented) hair at any body site, and is not androgen dependent.

Androgens and hirsutism

Hirsutism may be a sign of a significant medical disorder. Hirsutism is caused by increased androgen action on hair follicles. This may be a result of increased levels of circulating androgens or increased sensitivity of hair follicles to normal serum levels of androgens. Follicles start to develop thick, pigmented hair (terminal hair) as opposed to nonpigmented and thin hair (vellus hair) which is normally seen in these areas.

Causes of hirsutism include excessive production of androgens by the adrenals or ovaries; increased sensitivity of the hair follicles to androgens (which may be caused by exaggerated peripheral 5-alpha-reductase activity;, and functional abnormalities in the androgen receptors. Hirsutism is often a source of psychological discomfort as well, and most women who seek treatment for hirsutism do so for cosmetic reasons.

Hirsutism and hypertrichosis:

Hypertrichosis is a condition characterized by the growth of excess hair. Unlike hirsutism, excess hair growth in hypertrichosis is not restricted to androgen dependent areas. Many use these two terms interchangeably. But sometimes this leads to confusion in diagnosis.

Excess growth of body hair is normal in the following group of women.
  • Mediterranean
  • Indian
  • Dark haired Caucasian women

Causes of hirsutism:

Any condition that increases the blood level of testosterone, male sex hormone or androgens results in hirsutism.Testosterone stimulates hair growth and increases hair size and pigmentation. Testosterone acts on the hair follicles by converting in to its active form called dihydrotestosterone. 5 alpha reductase, the substance which is responsible for this conversion is found in these hair follicles.

The role of testosterone

Testosterone is secreted by the following two organs in the female body:
  • Adrenals - the organs sitting on the top of each kidney
  • Ovaries - the female organ which produces egg
After being secreted, testosterone travels in the blood attached to a protein called sex hormone binding globulin or SHBG. It is taken to the target areas where the protein releases the hormone. In the target areas, it gets converted into the active form - dihydrotestosterone.

Any condition which increases the secretion of testosterone or decreases the SHBG levels results in hirsutism. Some of the conditions causing hirsutism are
  • Polycystic ovary syndrome (POS or PCOS) - the most common ovarian cause
  • Congenital adrenal hyperplasia
  • Delayed adrenal hyperplasia
  • Cushing syndrome
  • Hyperinsulinemia
  • Hyperprolactinemia
  • Hypothyroidism
  • Ovarian tumors
  • Drug induced
  • Idiopathic or unknown - the most common cause

Disease statistics:

  • In the US, hirsutism is seen in 5-10% of women of reproductive age.
  • Globally, hirsutism is more common in Southern European and South Asian women in whom hirsutism is sometimes considered normal.
  • Hirsutism is usually seen in women after puberty, though in certain conditions like congenital adrenal hyperplasia, it may be seen during childhood itself.

Assessment of severity:

The severity of hirsutism can be assessed by the Ferriman Gallway model which assesses the hair growth in 9 anatomical areas. The areas included in this assessment are face, chest, areola, lower abdomen, upper back, lower back, buttocks, inner thighs and external genitalia. A score of 8 or more is abnormal and a score of 44, the most severe.


Treatment depends on the cause. If it is a simple hypertrichosis problem, only hair removal is done. If it is a full blown hirsutism, then the treatment includes
  • Hair removal
  • Anti androgen therapy
  • Diet modification to treat obesity
  • Surgery if the underlying cause is a tumor
Hair removal in hirsutism can be done by any of the following methods.
  • Depilatories
  • Temporary epilation
  • Permanent epilation
  • Laser hair removal
  • Non laser hair removal

Sometimes treating the underlying cause itself results in the removal of excess hair. For example, hirsutism due to drugs resolves itself if the drug intake is discontinued.

This page was last updated on June 20, 2006


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