most common cause of hair loss in men is called pattern baldness
(also called androgenetic alopecia or AGA). This is presented by the loss
of hair over the top (vertex) of the scalp. In this case, the specific mode
although the term pattern baldness denotes that both genetic predisposition
and the presence of androgens are necessary to cause expression.
Varying incidents of pattern baldness
in men induces an early hair loss phenomenon
that may take place any time after puberty.
In this stage, serum androgen levels in men
become naturally higher than in younger years.
The progression of men’s hair loss through
pattern baldness occurs in a distinct
pattern. On the affected areas, the transition
from large thick-pigmented terminal hairs
to thinner, shorter, indeterminate hairs and
finally to non-pigmented vellus (fine) hairs
gradually takes place.
A crucial clinical examination of the scalp
shows the extent and trend of the hair loss
- The first change in men with pattern baldness is usually seen with 96% of sexually
matured male Caucasians including those
who are not destined to progress in further
loss. This case is called bitemporal recession.
It comes through a gradual thinning in the
temporal areas followed by progressive thinning
in the frontal and vertex areas of the scalp.
of the frontal hairline is common.
- The frontal
and vertex thinning areas may unite together
resulting to the loss of
hair all over the crown.
The cases of hair loss in men become higher
over the years, although the rate can vary
dramatically from person to person. It may
also vary significantly over time. The intermediate
evolutionary stages between minimal thinning
and the stage when only a narrow horseshoe
shaped band remains exist because of the decrease
in hair density. The hair density of a normal
person varies between 200 and 400 hairs/ sq
cm while the hair density of a person affected
by pattern baldness is 50-150 terminal
hairs/ sq cm.
No one can tell what type of hair loss pattern
a young man with early pattern baldness
may assume. Generally, men who began losing
hair in the second decade are those with whom
alopecia will be most progressive. Initial
male pattern hair loss in some men may be
delayed until the late third to fourth decade.
The key to understanding the clinical presentation
of pattern baldness is to know the dynamics
of hair follicle cycling in normal as well
as balding scalp. A normal scalp has several
years average duration of the anagen (growth)
phase of hair, while the telogen (resting)
phase lasts 3 months. However, the pattern
hair loss in men has an altered growth cycle
that results to a progressive reduction in
the duration of the anagen phase. Consequently,
there is production of short, thin, hypo-pigmented,
insignificant wisps of hair, and the condition
becomes visible through the loss of scalp
Classification Pattern Hair Loss in Men
According to the classification developed
by Hamilton and Norwood, the clinical appearance
of pattern baldness in most men is widely and instantly
recognizable. These classifications were based
on the degree of hair thinning and the affected
areas of the scalp.
Hamilton established a classification based
on eight evolutionary aspects and three sub-groups.
He also made a comparison between the cases
of the Caucasians and the Chinese. In 1975,
Norwood recorded enhancements on the classification
that Hamilton established and made a more
detailed categorization, which is widely used
today. He divided androgenetic hair loss in
men into two common patterns: the Regular
Type, characterized by hair loss that begins
in two different areas - the temples and the
crown. These two gradually merge into one.
The Less Common Type is characterized by "front-to-back" hair
loss. In 1976, Bouhana proposed a simplified
classification of 5 evolutionary phases which
come from two sub-groups. This classification
allowed a more detailed evaluation of the
surgical indications of hair transplantations
in treating pattern baldness.
The scientific way of determining the rate
or amount of the degree of baldness in patients
is to compare the patient’s balding
pattern with the standard patterns described
by Norwood, which depict the most common configurations
of male pattern baldness. There are seven
grades of hair loss in the main series and
five grades of a variation called the "A" series.
As a rule, the pattern of a person’s
hair loss follows the specific type first
presented. In other words, a person who begins
as a Class 2 usually evolves into a Class
3, then a Class 4, etc. A Class 2a becomes
a Class 3a and then a Class 4a, and so on.
Other Facts about Male Androgenetic Alopecia
The occurrence of hair loss pattern in pattern baldness is characterized by both racial and
age-related differences. Studies show that
sexually mature Oriental and Native American
men tend to have more preservation of the
frontal hairline where baldness and less extensive
baldness usually occur in the first place.
Observation also shows that African-American
men may have a lower incidence and extent
of baldness with decreased frequency in fronto-parietal
The vertex balding seen in men is rare in
women. On the other hand, female pattern of
balding is not uncommon in men, the frequency
being higher in Asian men.