Autoimmune diseases, in which the body has an inappropriate immune response against things normally present in the body, are also responsible for hair loss in women. Lupus, for example, affects about 1.5 million people, and tends to strike women during their childbearing years. "The degree of hair loss can range anywhere from losing clumps while shampooing or brushing, to bald patches and a rash on the scalp." Alopecia areata is another autoimmune disorder in which the immune system specifically attacks hair follicles. "It affects about 4.7 million people in the United States, and occurs equally in men and women," says Marotta.

Solve It:
If you start to notice balding patches (usually circular or oval in shape), and tingling or pain on the scalp, head to your doctor for a diagnosis and safe recommendations for hair regrowth -- the same topical treatments that help with hair thinning are not recommended for hair loss associated with autoimmune diseases.

Many women who enter their doctor's office with complaints of hair thinning and hair loss often walk out with a thyroid disorder diagnosis. If your thyroid hormone levels are too low (hypothyroidism) or too high (hyperthyroidism), hair loss is a telling symptom that your levels are out of whack. "You'll usually find large amounts of hair falling out in the shower or sink, often accompanied by changes in the hair's texture -- drier than usual, more coarse or easily tangled -- these are all common symptoms of a thyroid disorder," Marotta explains.

Solve It:
If you suspect your thyroid is to blame, have your doctor check your thyroid levels, which can be done through a simple blood test. Fortunately, when it comes to hypothyroidism and hyperthyroidism, hair will return to its natural state once the thyroid imbalance is treated.