Alopecia Health Dictionary

See: HAIR LOSS. HAIR CARE. 

Loss or absence of hair, which may occur at any hair-bearing site on the body but which is usually noticeable only on the scalp.

Male-pattern baldness, the most common form of alopecia, is hereditary and most often affects men. Normal hair is lost initially from the temples and crown and is replaced by fine, downy hair; the affected area gradually widens. Other hereditary forms are rare. They may be due to an absence of hair roots or abnormalities of the hair shaft.

In generalized alopecia, the hair falls out in large amounts. Causes include various forms of stress, such as surgery, prolonged illness, or childbirth. Many anticancer drugs cause temporary alopecia. The hair regrows when the underlying cause is corrected.

Localized alopecia may be due to permanent skin damage (for example, by burns or radiotherapy) or trauma to the hair roots by styling or, rarely, trichotillomania (a disorder in which sufferers pull out their hair). The most common type of localized hair loss is alopecia areata, which is an autoimmune disorder. There is no specific treatment, but the hair usually regrows within a few months. Alopecia universalis is a rare, permanent form of alopecia areata that causes loss of all the hair on the scalp and body, including the eyelashes and eyebrows. Skin diseases such as scalp ringworm (see tinea), lichen planus, lupus erythematosus, and skin tumours may also cause localized hair loss.

Treatments for male-pattern baldness include hair transplants or drug treatments with minoxidil or finasteride.

Alopecia means hair loss. It may be localised or total in the scalp. The commonest type, which is hereditary, is male baldness (androgenic alopecia). Female balding spares the anterior hair line, develops later, and is less severe than the male variety. Di?use hair loss is common after childbirth, severe illness or infection (telogen alopecia); it begins 8–12 weeks after the causative event and recovery is complete. Persistent di?use hair loss may be caused by severe iron de?ciency or HYPOTHYROIDISM, or may be drug-induced.

Patchy localised hair loss is commonly caused by fungal infections (tinea capitis – see RINGWORM), especially in the tropics. It may also be due to trauma, such as hair-pulling by children or disturbed adults, or hair-straightening by African or Afro-Caribbean women (traction alopecia). Rarely, diseases of the scalp-skin such as discoid lupus erythematosus (see under LUPUS) or lichen planus (see under LICHEN) may cause patchy alopecia with scarring which is irreversible. The long-term effects of radiotherapy may be similar.

Treatment depends on the cause. Speci?c antifungal drugs cure tinea capitis. Correction of thyroid or iron de?ciency may be dramatic. Male baldness may be modi?ed slightly by long-term use of minoxidil lotion, or improved permanently by various types of hair-follicle grafting of transplants from the occipital scalp. Female balding may be amenable to anti-androgen/oestrogen regimens, but severe forms require a wig.

Loss of hair-a malady in which the hair falls from one or more circumscribed round or oval areas, leaving the skin smooth and white.

The loss of hair. Often occurs after treatment of cancer with chemotherapeutic agents.

The loss of hair.

(baldness) n. absence of hair from areas where it normally grows. Non-scarring alopecias include male-pattern balding, which is familial, and androgenetic alopecia in women, in which the hair loss is associated with increasing age. Acute hair fall (telogen effluvium), in which much or all of the hair is shed but may start to regrow at once, may occur after pregnancy or a serious illness. Alopecia areata consists of bald patches that may regrow; it is an example of an organ-specific *autoimmune disease. Alopecia totalis is loss of all the scalp hair, due to an autoimmune condition; in some 70% of cases it regrows within a few years. Alopecia universalis is loss of all body hair. In scarring (or cicatricial) alopecias the hair does not regrow; examples include *lichen planus and discoid *lupus erythematosus.