ALOPECIA, HAIR LOSS
alopecia (common baldness)
loss is universal and inevitable among all humans. Although the process is
virtually the physiologic norm, hair has such a powerful role in a person's
psychosexual self-image that anxiety about its loss may prompt him or her to
seek medical attention. Androgenetic alopecia (AGA) is the most common cuase of
hair thinning and occurs in both sexes when there is progressive miniaturization
of hair follicles, shortening of the anagen phase of the hair cycle, and
prolongation of the telogen phase. The scalp has a 3-phase cycle of hair with
almost 90% of hair in the anagen or growth phase (which may last up to 2-6
years), 1% in the catagen phase (which may last 3 weeks), and 10% in the telogen
or resting phase (which may last 3 months). This ratio is usually uniformly
distributed over the entire scalp.
The impact of hair loss on self-esteem is quite
different. Some tolerate it without any concern, while others find it to be
unacceptable when hair loss goes beyond culturally defined limits. This is due
to this great psychosocial impact,
that many patients may seek inappropriate and unproven therapies that are
available in nonmedical settings, often at great expense to the consumer.
is no question that genetic factors have a role in the development of
androgenetic alopecia, but the exact mechanism is not known. Inheritance in this
condition is most likely polygenic. There is increased frequency of AGA in sons
of men with AGA. The maternal influence on AGA is less well defined and the
family histories of women with AGA are not as straightforward as those of men
is a myth about role of blood flow in AGA.
This myth has been used to sell hair loss products as bizarre as a device
that allows you hang upside down in your closet overnight in order to restore
blood flow, but the fact is that blood supply is excellent in the scalp and
there is no need to enhance it!
brief, in AGA, hair loss occurs due to the action of circulating androgens in
genetically susceptible men and women. Although testosterone is the major
circulating androgen in men, its metabolite, dihydrotestosterone (DHT) is the
main culprit in AGA. The conversion of testosterone to DHT is mediated by an
enzyme called 5-alpha-reductase. Most women with AGA show no other clinical or
biochemical evidence of androgen excess.
of the hair begins between 12 and 40 years of age in both sexes, and
approximately 50% of the population expresses this trait to some degree before
50 years of age. Balding tends to begin earlier in men and to develop in
well-recognized patterns while female androgenetic alopecia is more diffuse and
less patterned than the forms seen in men.
treatment is recommended, patients should be carefully examined to establish the
diagnosis and rule out other causes of hair loss by history and physical
findings, as well as laboratory tests if needed.
diagnosis of AGA is usually made from the history and clinical findings alone.
Pull test may be positive in active early hair loss, but in the majority
miniaturization and decreased hair density are the only signs of AGA. Scalp is
also generally normal, however concomitant seborrheic dermatitis is common.
women, extensive hormonal evaluation may not be needed if the patient has no
menstrual irregularities, infertility, hirsutism, severe cystic acne,
virilization, or galactorrhea. If one or more of the above symptoms are present
in a woman, it may be useful to evaluate the hormonal status. However, in most
cases of female AGA, as in almost all cases of male AGA, there are no
alterations in the production of hormones and the problem lies in the target
organ, that is, how each hair follicle responds to circulating androgens.
obvious causes of hair loss, particularly in women, include thyroid disease and
other endocrine disorders, poor nutritional status, iron deficiency, drugs,
severe infection, systemic disease, malignancy, as well as other causes of
telogen effluvium. In addition to telogen effluvium, some variants of alopecia
areata and early cicatricial alopecia should also be kept in mind in
differential diagnosis of AGA.
A. General principles
Avoid hair care products likely to damage scalp/hair.
Keep an adequate diet, especially one with adequate protein.
If possible, any drugs that could negatively affect hair growth should be stopped. Hair loss is a common side effect of rRetinoids , cytotoxic agents and anticoagulants.
All therapies may need to be used indefinitely to maintain their effect.
Topical minoxidil solution: Topical
application of minoxidil offers unlimited hope but little practical benefit. It
must be used for 4 to 6 months before any results are seen, and new hair growth
is generally poor. When therapy is discontinued, the new growth soon falls out,
and patients return to their pretreatment condition. Mechanisms include
increasing the rate of mitosis of the follicle cells and prolonging the duration
of the anagen phase.
Minoxidil should be applied 1 mL twice daily on dry scalp and requires
about one hour to be absorbed.
Hair growth in areas other than that to which it has been applied is a
well-known phenomenon and may make more concern in women.
Topical minoxidil may also initially cause a temporary shedding which is
self-limiting and should not be a cause for concern.
If minoxidil is discontinued, any positive effect on hair growth will be
lost in 4-6 months.
FDA approved minoxidil for men > 18 years old.
Another topical drug that has shown results is
17 alpha-estradiol applied to the scalp once a
day. It was suggested that its action occurs from an aromatase stimulus, with
diversion of testosterone metabolism toward the production of 17 beta-estradiol,
leading to the reduction of dihydrotestosterone synthesis.
In certain selected cases, the following treatments may be helpful in women
only: oral estrogen,
(5a -reductase type 2 inhibitor): One milligram (1 mg) of finasteride, a
competitive inhibitor of 5-alpha-reductase type 2, taken orally, improves
predominantly vertex male pattern hair loss, and it is generally well tolerated.
Finasteride produces some regrowth of hair in about 2/3 of men. It is
contraindicated for women who are or may become pregnant, as it may cause
abnormalities to the external genitalia of the male fetus. FDA approved
finasteride only for men > 18 years old.
Surgical hair restoration, consisting of the
implant of mini- and micro-grafts (transplanting of single hairs or groups of 3
to 6 hairs in the occipital area), provides satisfactory results, and is
indicated in the most extensive cases of AGA.
Genetic therapy will probably be available in the next 10 to 20 years as an efficient treatment for AGA.