What Causes Hair Loss in Women?

Common or “hereditary” baldness in women appears to be related to the same major factors that cause hair loss in men:

* Genes
* Hormones
* Age

As is men, the genes that cause hair loss can be inherited from either your mother or father. The expression of these genes is dependent on hormones called androgens, so common hair loss in women is called “Androgenetic Alopecia” (the same term is used for common balding in men).

There are a number of reasons to explain why hair loss in women presents differently than in men (although all of the factors are still not completely understood). Probably the most important reason is that men have a much higher level of the androgen testosterone. This is the hormone that is responsible for male sexual characteristics and, when the body converts it to DHT, it becomes the main culprit in causing baldness. Fortunately, the much lower levels of testosterone in women spare them from the extensive hair loss that is often seen in men.

Testosterone is converted to DHT by the enzyme 5-alpha reductase that is present in higher concentrations in the balding areas of the scalp. Women have only ½ the amount of this enzyme overall as men and have even less in the crown. In addition, women have higher levels of an enzyme called aromatase in all areas of the scalp that may block the formation of DHT. This enzyme is present in especially high concentration in the frontal hairline in women, possibly explaining why this area is fortunately resistant to balding in most females.

With age some normal degree of hair loss occurs in everyone so that total hair volume will decrease over time in both sexes. The hair loss associated with genetic balding is also dependent upon time to express itself. Hair loss tends to occur at different rates at different periods in one’s life with increased loss often occurring during periods of hormonal change, such as pregnancy and menopause.

Other Causes of Diffuse Hair Loss in Women

A number of “non-androgenetic” factors may be responsible for hair loss in women. Women’s hair seems to be particularly sensitive to underlying medical conditions. Since “systemic” problems often cause a diffuse type of hair loss pattern that can be confused with genetic balding, it is important that women with undiagnosed hair loss, especially of the diffuse or “un-patterned” type, be properly evaluated.

Among the many medical conditions that can cause hair loss, the most common ones are:

* anemia
* thyroid disease
* other endocrine problems (especially those that produce excess androgens)
* gynecological conditions – such as ovarian tumors
* connective tissue disease (such as Lupus)
* surgical procedures and general anesthesia
* rapid weight loss or crash diets that are not nutritionally balanced
* severe emotional stress

It is also important to review the use of medications that can cause hair loss. The more common ones are:

* oral contraceptives
* thyroid medication
* blood pressure medication (such as beta-blockers or water pills)
* “mood” medication such as lithium, Prozac, or tri-cyclic antidepressants
* blood thinners such as heparin or coumadin
* cholesterol lowering medication
* medication for gout, such as Zyloprim
* anti-inflammatory drugs such as cortisone
* vitamin A or tryptophan in high doses
* street drugs (such as cocaine)

Laboratory Evaluation in Women

The decision of when to perform a laboratory evaluation in women experiencing hair loss must be made on an individual basis by your physician. In this section we briefly describe some of the situations where your doctor may order lab tests and what they might be. It is important to stress that this is just an overview for your general information. When a physician orders laboratory tests he/she bases it upon specific clinical information and this can only be determined by the doctor who evaluates you.

The following signs and symptoms suggest that specific blood tests might be appropriate to rule out underlying sources of excess androgen:

* Irregular periods – for an extended period of time
* Cystic acne – severe acne which usually leaves scars
* Hirsuitism – increased body hair that doesn’t normally run in your family
* Virilization – appearance of secondary male sex characteristics such as a deepened voice
* Infertility – inability to become pregnant
* Galactorrahea – breast secretions when not pregnant (this is due to prolactin which is not actually an androgen)

Some of the tests that your doctor might order in these situations include the following:

* Total and Free Testosterone – the hormone that is mainly responsible for male secondary sex characteristics
* DHEA-Sulfate – a precursor to testosterone
* Prolactin – the hormone that enables the breast to secrete milk

Other test that are commonly ordered for underlying medical conditions include:

* CBC (complete blood count) – for Anemia
* Serum iron (and TIBC) – for Anemia
* T3, T4, TSH – for Thyroid disease
* ANA – for Lupus
* STS – for Syphilis


For more information, see the following information: