Diseases that can cause hair loss, thinning, or breakage include:
Lupus, in which hair tends to become brittle and may fall out in patches. Short, broken hairs ("lupus hairs") commonly appear above the forehead. Hair loss is usually not permanent. Some people with lupus also develop a form of lupus called discoid or cutaneous lupus that affects only the skin ("cutaneous" refers to skin). Scars that sometimes develop on the scalp may cause hair loss.