Partial or complete loss of hair is called alopecia.
Loss of hair; Alopecia; Baldness; Telogen effluvium
Hair loss usually develops gradually and may be patchy or all over (diffuse). You lose roughly 100 hairs from your head every day. The average scalp contains about 100,000 hairs.
Each individual hair survives for an average of 4 1/2 years, during which time it grows about 1/2 inch a month. Usually in its 5th year, the hair falls out and is replaced within 6 months by a new one. Genetic baldness is caused by the body's failure to produce new hairs and not by excessive hair loss.
Both men and women tend to lose hair thickness and amount as they age. Baldness is not usually caused by a disease. It is related to aging, heredity, and testosterone. Inherited or "pattern baldness" affects many more men than women. About 25% of men begin to bald by the time they are 30 years old, and about two-thirds are either bald or have a balding pattern by age 60.
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Reviewer Info: Michael Lehrer, MD, Department of Dermatology, University of Pennsylvania Medical Center, Philadelphia, Pa. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.; ADAM Health Illustrated Encyclopedia, 05/07/2009 |