Hair loss on the legs can be caused by several medical conditions, although the two most prominent and prevalent conditions are alopecia areata and peripheral artery disease of the legs. Although the cause of alopecia areata is unknown, peripheral artery disease of the legs is caused by hardening and narrowing of the arteries.
Alopecia areata is thought to be an autoimmune condition where the body attacks its own cells, causing patches of hair loss in various parts of the body, particularly in the legs. About one in five people have a family history of a type of alopecia. Peripheral artery disease of the legs causes loss of blood flow, which is responsible for stimulating hair growth.