Hair loss frequently affects the well-being and self-esteem of both men and women. For women, hair loss is just as psychologically distressing as it is for men, if not more. Unlike hair loss in men, female hair loss may commonly begin at any age through 50 or later, may not have any obvious hereditary association, and may not occur in a recognizable pattern of diffuse thinning over the top of the scalp. The hair loss may be temporary or permanent.

In women as in men, androgenic alopecia can be blamed for hair loss in the majority of cases. Androgenetic alopecia is an inherited sensitivity to the effects of androgens (male hormones) on scalp hair follicles, which can begin as early as the late teens to early 20s in women who have experienced early puberty. Early puberty hair loss can progress to more advanced hair loss if left untreated. Fortunately, women with hair loss due to this cause usually do not develop the extensive hair loss patterns that occur in men.

When not caused by androgenic alopecia, hair loss can be caused by a wide range of conditions including alopecia areata, hypothyroidism, post pregnancy and chemical processing. It can manifest itself as a diffuse thinning all over the scalp rather than following a particular pattern as it does in men. M edical evaluation is an important first step in investigating the underlying cause of the problem and determining the most optimal course of treatment.

As found in male pattern baldness, common or "hereditary" baldness in women seems to be related to genetic disposition, hormones and age. As in men, the genes that cause hair loss can be inherited from either the mother or father. Hereditary baldness is dependent on hormones called androgens acting on genetically susceptible hair follicles in the scalp, so common hair loss in women is called "Androgenetic Alopecia".

While the variables affecting female hair loss are not completely understood, there are a number of reasons that explain why hair loss in women presents differently than it does in men. Fortunately, testosterone levels in women are much lower than they are in men, making them less likely to develop the extensive hair loss often experienced by men.

When testosterone is chemically altered by the enzyme 5-alpha reductase in the skin, it becomes a more potent hormone, known as dihydro-testosterone(or DHT). Fortunately, w omen have only 50% of this enzyme as compared to men and have even less in the crown. Women also have higher levels of an enzyme called aromatase in all areas of the scalp that is thought to possibly block the formation of DHT. This enzyme is present in especially high concentration in the frontal hairline in women, which might be the reason for this area being resistant to balding in most women.

DHT acts by binding to special receptor sites on the cells of the hair follicles. The effect is not immediate, however. Susceptible hair follicles must continually be exposed to DHT over a period of time for hair loss to occur.

Once the effect begins to manifest itself, the length of the anagen (growing) cycle of the hair shaft decreases, and the telogen (resting) phase of the hair shaft lengthens. Genetically susceptible hair follicles that were producing healthy, terminal hairs will begin to produce thinner, shorter, more brittle hairs with weaker shafts ("miniaturization"). As the condition continues, the follicles produce finer and finer hairs, until they become almost invisible, short, vellus hairs, or die out altogether. Thinning scalp hair in women due to androgenetic alopecia does not uniformly grow smaller in diameter (miniaturize) as it does in men. Women with this type of hair loss usually have miniaturizing hairs of variable diameter over all affected areas of the scalp.

Miniaturization of hairs may occur for other reasons in women so the presence of miniturization cannot be used to diagnose androgenetic alopecia. For example, post-menopausal women will often experience miniaturization and note that their hair has become difficult to style.

Accelerated hair loss does not occur at a consistent rate or all at once, but rather in cycles. People who are losing their hair experience alternating periods of slow and rapid hair loss as well as periods of relative stability.. In women, there is often a period of accelerated loss during times of hormonal change, such as pregnancy and menopause. Many of the factors that cause the rate of loss to accelerate or decelerate are unknown.

The classification system widely used to assess the degree of hereditary baldness in women is called the Ludwig scale and is shown below. As is evident in the illustration, the pattern of hereditary hair loss in women is much different from that seen in men.

THE LUDWIG SCALE FOR WOMENS HAIR LOSS