Up to 50 percent of women will experience female pattern hair loss during their lifetime. 1 Patients usually present with hair thinning over the central area of the scalp and widening of the midline part, but with reservation of the frontal hairline ( Figure 3 ). Women who also have abnormal menses, history of infertility, hirsutism, unresponsive cystic acne, virilization, or galactorrhea should have a targeted endocrine work-up for hyperandrogenism (., testosterone, dehydroepiandrosterone sulfate, and prolactin), although most will have normal androgen levels. 29 Evaluation for iron deficiency, thyroid disease, and syphilis (a rare cause) should be considered because they can contribute to hair thinning or generalized hair loss.
During a very stressful time, your body may react by causing more hairs than normal to go into resting phase. The medical term for this condition is telogen (tee-lə-jen) effluvium (ih-flu-vee-uhm). During telogen effluvium, the body sheds a dramatic amount of hair. For most people, the hair will start to grow again without any help.
4. Make an appointment to see a dermatologist. Many things can cause hair loss. If hair loss concerns you, be sure to see a dermatologist. A dermatologist can find the cause and tell you what you what to expect.
A key aspect of hair loss with age is the aging of the hair follicle.  Ordinarily, hair follicle renewal is maintained by the stem cells associated with each follicle. Aging of the hair follicle appears to be primed by a sustained cellular response to the DNA damage that accumulates in renewing stem cells during aging.  This damage response involves the proteolysis of type XVII collagen by neutrophil elastase in response to the DNA damage in the hair follicle stem cells. Proteolysis of collagen leads to elimination of the damaged cells and then to terminal hair follicle miniaturization.