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    Oh, by the way...why am I losing my hair?

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    Nancy is a 22-year-old who is seeing you for her annual visit and preconception counseling. When she decided to get pregnant 9 months ago, she stopped her Depo-Provera injections. Her cycles are now regular in timing and duration. She and her husband are currently using condoms. She denies any recent unexplained weight loss or gain. Her vital signs and gynecologic exam are unremarkable. As you are leaving, she looks up and asks, "Oh, by the way, why am I losing my hair?"

    Some women are preoccupied with their hair, and the thought of going bald is naturally quite distressing. Hair loss can result from damage to the follicles or hair shaft, and can occur at any point in the hair's growth cycle. Figure 1 illustrates practical approaches to the problem, depending on whether the loss is sparse or more widespread.

    The key questions you'll need to answer to help Nancy are:

    • How long ago did the hair loss start?
    • Is the loss patchy or diffuse?
    • Is the dermis inflamed but unscarred or atrophic and scarred?

    If your patient's scalp is atrophic and scarred, it's unlikely her hair will grow back. But because Nancy is young, her hair loss probably is caused by stress or hormones. There are other conditions, too, that need to be included in your differential diagnosis.

    Why hair does—or doesn't—grow


    Figure 1. How to manage hair loss
    An understanding of hair loss is "rooted" in the basic physiology of hair growth. A hair follicle's active-growth phase, called anagen, lasts up to 7 years. The resting phase, when hair growth stops—telogen—lasts 2 to 4 months. When the follicle re-enters anagen, a new hair shaft is started and pushes out the old one. At any given time, most of our hair is in the anagen phase, and on average, we lose about 100 hairs a day due to hair follicles at the end of their telogen phase.

    Diffuse hair loss typically occurs because of an insult to the normal growth cycle, which shortens the anagen phase or leads to more follicles than usual entering telogen at the same time. Ob/gyns often see patients who have stress alopecia or telogen effluvium. In this condition, a stressor causes a large number of hair follicles to enter telogen at the same time. Two to 3 months after the stressor, hairs in telogen will be shed as new hairs grow out. A "sudden" diffuse hair loss is common about 3 months after pregnancy. Hormonal contraceptives can also be associated with it, particularly in the months after a woman stops taking them. Other common causes of stress alopecia include high fever (41°C or more), certain medications, acute trauma, surgery, and severe dieting.

    Is it stress alopecia or alopecia areata?

    To diagnose stress alopecia, take a good history from your patient and run your fingers through a small portion of her hair and see how many hairs come out. If many hairs are shed, the hair loss process is probably active and expanding. Next, look at the patient's scalp to rule out patchy patterns of hair loss, which are indicative of a cause other than stress. Conversely, if there is diffuse hair loss and the ends of the hair shafts that fall out have a clubbed appearance, it's likely stress alopecia.

    Treatment consists of reassuring your patient that she is NOT going bald, within a couple of months the loss will decrease, and the thickness of her hair will gradually return to normal.

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    Sharon T. Phelan, MD
    Dr. Phelan is a Professor in the Department of Obstetrics and Gynecology, University of New Mexico, Albuquerque.

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