When people hear the words hair loss their first thought is usually the hair on someone’s scalp but hair loss can affect many people in many different ways. There are countless diseases, disorders, and drugs that have caused hair loss over different areas of the body.

Chemotherapy Treatments: Chemotherapy drugs are powerful medications that attack rapidly growing cancer cells. Unfortunately, these drugs will also attack other rapidly growing cells in your body like those in your hair roots. While chemotherapy drugs are most often associated with losing the hair on your scalp, these drugs may cause your eyelash, eyebrow, armpit, and other body hair to fall out as well. Chemotherapy doesn’t always guarantee hair loss and certain drugs are more likely than others to cause hair loss and different doses can cause anything from thinning hair to complete baldness. Fortunately, most of the time hair loss from chemotherapy is temporary and your hair should grow back three to six months after your treatment ends.

Alopecia Areata: Alopecia areata is an autoimmune disease. Normally a person’s immune system protects the body against infection and disease but when someone has an autoimmune disease their body’s immune system attacks some part of their own body. With alopecia areata the immune system attacks a person’s hair follicles, in most cases the hair will fall out in small, round quarter size patches. Some people may lose more hair and in rare cases the disease can cause someone to completely lose the hair on their head, face, and body. Anyone can have alopecia areata and while it’s currently unknown what specifically causes this disease scientists believe genetics may have something to do with it. While there is currently no cure for alopecia areata and there are no drugs approved to treat it doctors may use medicines approved for other diseases to help hair grow back. However, none of these treatments prevent new patches of hair loss or cure the disease.

Thyroid Disorders: Due to the hormones it produces, the thyroid gland influences almost all of the metabolic processes in the body. The most common thyroid problems include both an underactive thyroid gland (hypothyroidism) and an overactive thyroid gland (hyperthyroidism). Proper hair growth depends on the proper functioning of the thyroid gland and abnormal levels of thyroid hormones can cause many side effects including hair loss. Having too much thyroid hormones can cause thinning hair all over the scalp and having too little thyroid hormones can cause hair loss all over the body. Once your thyroid disease is diagnosed it may take some time to get the right dosage but once you find the right prescription to help regulate your thyroid hormone levels the hair loss problem should resolve itself.
   

http://www.mayoclinic.org/tests-procedures/chemotherapy/in-depth/hair-loss/art-20046920
http://www.niams.nih.gov/health_info/Alopecia_Areata/alopecia_areata_ff.asp
http://www.everydayhealth.com/skin-and-beauty/thyroid-disease-and-hair-loss.aspx