Hair loss is often a normal and expected part of aging. Hair naturally thins with age, and hormonal changes and genetic influences can lead to hair loss, particularly in men. But the aging process does not explain excessive or abnormal hair loss, also known as alopecia. When hair loss is specific to a certain body area -- such as the legs -- a common cause is poor circulation. However, illness, medications, follicular damage and friction are other known causes. Sometimes the cause is unknown. See your doctor to evaluate any new or sudden hair loss.
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Friction and Scarring
Hair loss can occur as a result of friction caused by jeans, tight socks or even tight bicycle shorts. Friction can discourage hair growth over time, or break hair follicles near the skin. In these cases, the hair will regrow when the damage stops occurring. Also, hair doesn't grow on scar tissue. Burns, scars or persistent eczema or skin rashes can cause damage to the hair follicles, preventing hair growth in this area.
A common cause of hair loss in the legs is peripheral artery disease (PAD), which is poor circulation caused by the buildup of plaque and narrowing of the arteries that supply blood to the legs and feet. Hair loss occurs because the impaired blood supply is not able to provide optimal nutrients for hair growth. According to the Centers for Disease Control and Prevention (CDC), 12 to 20 percent of adults over the age of 60 have PAD, a condition more common in smokers, and in people with diabetes, heart disease, high cholesterol and high blood pressure. Other physical symptoms of PAD include smooth, shiny skin and a cooler skin temperature.
Other Medical Conditions
Anterolateral leg alopecia, a seemingly harmless cause of lower leg hair loss, is common in middle-aged and older men, according to the April-June 2014 issue of "International Journal of Trichology." Alopecia areata is an autoimmune disease that causes round patches of hair loss, often the size of a quarter, which can occur anywhere on the body. A more severe but rare form of this condition, called alopecia universalis, causes hair loss all over the body.
Some other diseases can cause hair to stop growing, although most of this hair loss is not specific to the legs. For example, thyroid disorders or severe malnutrition caused by illness or eating disorders can cause hair loss all over the body.
Certain medications cause hair loss and prevent hair growth -- symptoms that usually resolve when you stop taking the medication. Chemotherapy drugs target rapidly growing cancer cells, and since hair cells also grow rapidly, they may also fall victim to these drugs. People with cancer may lose not only the hair on their heads, but eyebrows, eyelashes and hair on other parts of the body. According to the American Academy of Dermatology, other medications that can lead to all-over hair loss include birth control pills, blood thinners, anabolic steroids, high dose vitamin A, and drugs used to treat high blood pressure, depression, gout and heart problems.
If you are experiencing rapid or significant hair loss, see your doctor. Sometimes hair loss does not need treatment, and if the cause is identified, the hair may grow back in time. If your hair loss is related to poor circulation or an illness, managing these conditions is a priority. Contact your doctor if your hair loss is associated with any pain, itching, redness or any other unusual symptoms.