Presence of excessive bodily and facial hair, usually in a male pattern, especially in women; may be present in normal adults as an expression of an ethnic characteristic or may develop in children or adults as the result of androgen excess due to tumors or drugs, or nonandrogenetic drugs.
Eg : growth of hair on the face, chest and areola in men is normal; growth of hair in those places in women is abnormal
Hirsutism can be caused by abnormally high androgen levels or by hair follicles that are more sensitive to normal androgen levels. Therefore, increased hair growth often is observed in patients with endocrine disorders characterized by hyperandrogenism, which may be caused by abnormalities of the ovaries or the adrenal glands.
The physiologic mechanism proposed for androgenic activity consists of the following 3 stages:
- Production of androgens by the adrenals and ovaries
- Androgen transport in the blood on carrier proteins (principally sex-hormone–binding globulin [SHBG])
- Intracellular modification and binding to the androgen receptor
In short, central overproduction of androgen, increased peripheral conversion of androgen, decreased metabolism, and enhanced receptor binding are each potential causes of hirsutism. For circulating testosterone to exert its stimulatory effects on the hair follicle, it first must be converted into its more potent follicle-active metabolite, dihydrotestosterone. The enzyme, 5-alpha-reductase, which is found in the hair follicle, performs this conversion.
Overproduction of androgens results in an increased hair follicle size, hair fiber diameter, and duration of time hair follicles spend in the anagen (growth) phase. In addition to a change in hair quality and volume, oilier skin and hair may result from excess androgen secretion. The distribution of hair in women with high androgen levels is also altered. Excessive hair growth occurs in androgen-sensitive regions, but hair loss occurs on the scalp.1
The severity of hirsutism does not correlate directly with the level of increased circulating androgens because of individual differences in conversion to 5-alpha-reductase and androgen sensitivity of hair follicles.
Testosterone stimulates hair growth, increasing the size and intensifying the pigmentation of hair. Estrogens act in opposition, slowing growth and producing finer, lighter hairs. Progesterone has minimal effect on hair growth.
The amount of free testosterone—the biologically active androgen that, after conversion to dihydrotestosterone, causes hair growth—is regulated by SHBG. Lower levels of SHBG increase the availability of free testosterone
Can be broadly classified in to five categories:
- Hormone system related
- Tumor related
a) Hormone system related causes of hirsutism:
The hormone or the endocrine system is a delicately managed system with wonderful feedback controlled by the pituitary gland and the hypothalamus of the brain. Secretion of androgens is also under the control of this system. Any perturbation in it can change the blood levels of the androgens.
Androgens are normally secreted by the adrenals and the ovaries in women.
The causes of hirsutism under this category include:
- Cushing’s syndrome – defined as excess secretion of steroids including androgens
- Congenital adrenal hyperplasia – An enzyme deficiency leading to excess production of androgen
- Acromegaly – Excess growth hormone and insulin resistance
- Hyperprolactinemia – Increased prolactin levels
- Hypothyroidism – There is a decrease in the thyroid hormone levels
- Polycystic ovarian disease – This is an ovarian disease with multiple cysts and increased blood androgen levels
b) Tumor related causes of hirsutism:
Tumores of the ovaries and the adrenal glands secrete excess hormones including androgen.
The causes of hirsutism under this category include:
- Ovarian tumors
- Granulosa -theca cell tumors
- Adrenal tumors
- Adrenal adenoma
- Adrenal carcinoma
c) Drugs causing hirsutism:
There are certain drugs which increase body hair. The distribution of excess can be limited to androgen sensitive areas or both androgen and non androgen responsible areas. A condition when excess hair also occurs in non androgen sensitive areas is called hypertrichosis.
Drugs causing hirsutism are:
- Minoxidil – vasodilator medication to slow or stop hair loss and promote hair regrowth
- Phenytoin – antiepileptic
- Cyclosporine – immunosuppressant
- Diazoxide – vasodilator in the treatment of hypertension
- Oral contraceptives – containing progesterone
- Penicillamine – treat rheumatoid arthritis.
- Heavy metals
- Acetazolamide – to treat glaucoma, epileptic seizures,benign intracranial hypertension (pseudotumor cerebri)
d) Miscellaneous causes of hirsutism:
This category consists of diverse causes which cannot be grouped under other categories.
Causes of hirsutism under this category include:
- Syndromes of excessive insulin resistance
- Functional adrenal hyperandrogenism
- Hypereactio luteinalis of pregnancy – transient increase in androgen levels during pregnancy
- Thecoma of pregnancy – Transient androgen secreting tumor during pregnancy
- True hermaphroditism – condition where both male and female internal sex organs are present
e) Unknown causes of hirsutism:
In the unknown or the idiopathic category, the causes of hirsutism are not known. The affected person is healthy till puberty and thereafter develops hirsutism. In this category the hirsutism is usually familial. There will be an associated obesity and insulin resistance. Some of the patients in this category have normal blood androgen levels. In these patients the cause of hirsutism is increased sensitivity of the body to normal androgens.
- The most widely accepted method of quantitation uses the Ferriman and Gallwey scale. However, use care because this method has significant interobserver variability. In this approach, hair growth is judged in each of 11 androgen-sensitive areas.
- The grade for each area ranges from 0 (no terminal hair) to 4 (frankly virile).
- The body areas used to grade hirsutism are (1) the upper lip, (2) chin, (3) chest, (4) leg, (5) thigh, (6) upper arm, (7) forearm, (8) upper back, (9) lower back, (10), upper abdomen, and (11) lower abdomen.
- Areas such as the axilla and pubis are not included because terminal hair grows in these places at normal androgen levels in women.
- The total score correlates roughly with the elevation of androgen levels. A woman with a score of 8 or higher is considered to have hirsutism. Most women who seek medical attention for the disorder have scores of 15 or higher. Normal scores have also been established for Turkey (up to 11) and Thailand (up to 3 on the modified Ferriman and Gallwey scale).
- In women with moderate-to-severe hirsutism (score >15), seek additional signs of hyperandrogenism, including (1) temporal hair recession, (2) oily skin, (3) masculine voice, (4) well-developed musculature, (5) enlargement of the clitoris (>35 mm2 in surface area), (6) irregular menses, and (7) psychological changes (eg, heightened libido, aggressiveness)
Additional info on grading : http://humupd.oxfordjournals.org/content/16/1/51.full.pdf