Encyclopedia of Health and Medicine

alopecia 137
tions. Common forms of alopecia include the following:
• Androgenic alopecia, or male pattern hair loss,
in which a man’s hairline recedes from the
temples and forehead and thins on the crown
in a characteristic pattern that may culminate
with a fringe of hair remaining along the sides
and back of the head. Hair loss is permanent.
Androgenic alopecia is hereditary and commonly
begins in midlife, though may begin as
early as a man’s mid-20s. Researchers believe
androgenic alopecia results from a combination
of genetic predisposition and naturally declining
TESTOSTERONE levels.
• Female pattern alopecia, in which a woman’s
hair gradually thins on the top and sometimes
back of her head. Hair loss is permanent.
Researchers believe female pattern alopecia
results from hormonal changes (loss of ESTRO-
GENS and testosterone) that occur following
MENOPAUSE.
• ALOPECIA AREATA, an autoimmune disorder in
which the body’s IMMUNE RESPONSE attacks clusters
of hair follicles, temporarily impairing their
ability to produce new cells. Alopecia areata
may affect any part of the body and occasionally
the entire body. Hair loss is temporary,
though may be long term.
• Toxic alopecia, which results from exposure to
substances that impair the ability of the hair
follicles to generate new cells. The most common
sources of such exposure are radiation
therapy and chemotherapy treatments for cancer.
Other causes include vitamin A toxicity
and medication side effects, such as from
retinoid preparations to treat acne. The extent
of hair loss depends on the toxic agent, ranging
from localized (such as with radiation therapy
to the head) to nearly complete (such as with
chemotherapy). Hair growth returns when the
toxic exposure ceases.
Scarring, such as occurs as a result of BURNS,
wounds, and certain AUTOIMMUNE DISORDERS,
destroys the hair follicles so hair loss in such areas
is permanent. Conditions and circumstances that
damage but do not destroy the follicles often allow
hair growth to resume. Medical treatments that
stimulate follicle activity can accelerate the return
of hair in many such situations.
CONDITIONS ASSOCIATED WITH ALOPECIA
radiation exposure
CHEMOTHERAPY
TRICHOTILLOMANIA
tinea capitis
PREGNANCY
MENOPAUSE
HYPOTHYROIDISM
high FEVER
INFECTION or serious illness scars from wounds or BURNS
excessive hair care and styling SUNBURN and sun exposure
AUTOIMMUNE DISORDERS
DISCOID LUPUS ERYTHEMATOSUS
hormonal changes
(DLE)
SYSTEMIC LUPUS
MALNUTRITION
ERYTHEMATOSUS (SLE)
hair coloring and styling
stress
products
FOLLICULITIS
Symptoms and Diagnostic Path
Hair loss is the primary symptom of alopecia. The
pattern and rate of hair loss help determine the
nature of the underlying cause. When alopecia is
male pattern or female pattern hair loss, the doctor
can make the diagnosis on the basis of appearance.
When the cause of hair loss is uncertain, the
doctor may biopsy several sites on the scalp, both
with and without hair, for microscopic examination.
A comprehensive health history and medical
examination are important to identify any potential
systemic or general health causes for hair loss.
Preliminary findings determine what, if any, further
testing is necessary.
Treatment Options and Outlook
Treatment first targets any underlying condition
that may be responsible for hair loss. In many situations
of alopecia related to other health conditions,
hair growth will resume without medical
intervention. People who are sensitive about their
appearance during the period of temporary alopecia
may choose to wear hairpieces, hair weaves,
wigs, scarves, or hats until their hair returns. Topical
products to stimulate hair growth, such as
minoxidil (Rogaine) and finasteride (Propecia),
sometimes hasten the return of hair follicle function.
Such products are often the first choice of
treatment for male or female pattern hair loss as
well as many forms of nonscarring alopecia. However,
hair growth typically continues only for as
long as treatment continues.