Normal hair growth
About 90% of scalp hair is continually growing and 10% is resting. At the end of the resting phase, the hair is shed. Shedding 50 to 100 hairs a day is normal. When a hair is shed, it is replaced by a new hair from the same follicle located just below the skin surface. Scalp hair grows about one-half inch a month. As people age, their rate of hair growth slows down.
When should I see a dermatologist?
People who notice they are shedding large amounts of hair after combing or brushing, or whose hair rapidly becomes thinner or falls out in patches should consult a dermatologist. The dermatologist will evaluate the problem by asking questions about diet, medications, family history, recent illness and hair care habits. Female patients will be questioned about menstrual cycle, pregnancies, and menopause. After examination of the patient's scalp and hair, the dermatologist may examine a few hairs under the microscope. Laboratory tests are sometimes required. It is important to understand why hair is being lost and whether or not the problem will respond to medical treatment.
What are some causes of abnormal hair loss?
Childbirth, high fever, severe infection, severe flu, thyroid disease, inadequate protein in the diet, medications, cancer treatment drugs, birth control pills, low serum iron, major surgery or chronic illness, alopecia areata, hereditary thinning or balding, ringworm of the scalp and improper hair cosmetic use and improper hair care can all lead to abnormal hair loss.