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Question: Why do men go bald and women do not?
Hair grows from its follicle about the rate of one half inch per month. Each hair grows on the average for about 5 years, rests, then falls out. At any one time, 85% of the hair is growing and 15% is resting. We lose about 10,000 scalp hairs every day. Baldness, or alopecia, occurs when the rate of hair falling out exceeds hair growing in. It can be associated with genetic predisposition, aging and alternating levels of androgens, the male sex hormones.
In balding, the hair follicle becomes smaller and the hair that grows from the follicle miniaturizes, loses its pigmentation and decreases the time it spends in the growth phase, which goes from 2-5 years to a month or two for really fine hair, sometimes called "vellous" hair. The terminal stage in balding involves atrophy and fibrosis of the hair follicle.
The typical pattern that occurs in women particularly around and after menopause is that the hair thins all over the head. Oddly enough, the frontal hairline remains intact. On the crown of the head there may be a moderate loss or thinning, but rarely does this progress to total baldness, as it occurs in men. Other reasons that may cause baldness in women are: breaking of hair follicles from twisting or pulling the hair, patchy areas of hair loss called alopecia areata, which is an immune disorder causing temporary hair loss. Certain medications can also cause hair loss.
In males, hair loss can start in different areas of the head but more often starts in the temple area or on the crown of the head. In males, it is the effects of hormones on the hair follicle that produces alopecia. The hormone testosterone, present in males in high levels after puberty, is converted to dihydrotestosterone (DHT) by an enzyme called 5-alpha reductase. DHT makes the hair follicle slow down and renders it weak. The follicle then produces shorter hair growth. Sometimes it stops hair growth completely causing baldness.
It is important to remember that it is not normal if your hair falls out in clumps when you wash your hair or after sleeping at night. Other causes of hair loss include: thyroid and pituitary problems, birth control pills, childbirth, radiotherapy, chemotherapy, steroids, stress. Medications such as interferon, ringworm or fungal infections of the scalp, burns, or high temperature associated with the flu or infections can also cause hair loss.
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