Genetic hair loss in women

In women, there’s a distinct relationship between mother, sisters,
aunts, and grandmothers when it comes to thinning hair patterns.
When we take a careful history from women with thinning hair, far
more than half of the women we interview with balding or thinning
have female relatives with a similar problem. When one recognizes
this in the family history, we generally ask these women to inquire
on the course of the family balding patterns from a timeline
perspective.
Genetic hair loss is relatively uncommon in women and is generally
referred to as female pattern hair loss or female androgenetic alope-
cia. In women with this condition, the common pattern differs than
that of men. Whereas the pattern in men follows the Norwood clas-
sification (refer to the earlier section, “Norwood classifications for
measuring male pattern thinning”), the postmenopausal pattern in
women is characterized by diffuse thinning starting just behind a
normal hairline and extending to and beyond the swirl.
Unlike men, adult women with typical female postmenopausal
androgenetic alopecia often have significant levels of miniaturiza-
tion (decreased hair shaft thickness in some hairs and loss of hairs
within the follicular unit) in the back and side of the scalp.
Miniaturization causes hair shafts to become thinner over time
before falling out, and the higher degree of miniaturization present
indicates an unstable hair loss process throughout the scalp.
In some women, the genetic pattern of hair loss is associated with
an increase in male sex hormones (androsterone, testosterone, and
DHT), but in most cases of genetic hair loss, it occurs when the sex
hormone levels are normal.
Compared to men, the mechanism of balding in women is less well
understood because their hair loss isn’t as directly related to the
presence of DHT. The enzyme aromatase appears to have a role in
causing female hair loss and may partially explain the different pat-
tern when compared to men. The loss of estrogens in post-
menopausal women means that the protection against female
genetic alopecia is withdrawn, bringing on the thinning.
Women who develop pattern balding later in life also have a
genetic component to their hair loss, but the association is less
strong. The changes in hormones that occur around menopause
are an obvious contributing factor.
Because genetic hair loss presents itself differently in women than
in men, a different classification system is used. Doctors use the
Ludwig classification to describe the thinning that women experi-
ence. A Ludwig type I is associated with a mild widening of the part
width. Patients who fall into type II have increased thinning with
moderate widening of the part. Type III patients have significant
widening of the part width. Figure 4-3 depicts types I through III.
A minority of women develop pattern balding in a distribution
that’s similar to men. These patients are better classified using the
Norwood classification system. Because these women have hair
loss mainly limited to the front and top of the scalp that doesn’t
affect the back and sides, they may be candidates for hair trans-
plant surgery, which we discuss in Chapter 13. About 15 percent of
women have this patterned balding.