Excess hair loss can have many different causes. People who notice their hair shedding in large amounts after combing or brushing may be experiencing some form of hair loss.
Hair grows in cycles. Every hair is constantly in one of three phases resting, growing, or shedding. During the growing, or anagen phase, there is a continual division of living cells in each hair root promoting new growth.
At the end of the growing process, hair goes into the resting, or telogen, phase in which cells stop dividing and hair growth ceases. About 10-15% of one's hair is constantly in this phase.
During the shedding phase, the hair separates from the root and begins to fall out. The hair you find in your comb or brush was in this stage. Shedding 50-100 hairs a day is normal. This entire resting/shedding phase lasts from 2-6 months. When a hair is shed, it is replaced by a new hair from the same follicle and the growing cycle starts again.
Scalp hair grows about one-half inch a month. As people age, their rate of hair growth slows.
When addressing hair loss, a full medical history and close examination of the scalp will be required. Questions regarding diet, medications, including vitamins taken in the past six months, family history of hair loss, recent illness and hair care habits will be asked.
A laboratory work-up and even a scalp tissue biopsy may be required in some cases.
Female/Male Pattern Baldness
Hereditary hair loss is the most common cause of thinning hair. Women with this trait develop thinning hair, but do not commonly become completely bald. The condition is called androgenic alopecia.
The male hormone testosterone, when exposed to the enzyme “5-a-reductase,” located in the hair follicles, metabolizes testosterone and produces another hormone derivative dihydrotestosterone (DHT). On certain parts of the scalp, as predestined by genetics, the hair follicles automatically seek out the DHT hormone. These follicles literally overdose on DHT causing them to shrink. With this shrinkage, the hair undergoes shortened growth cycles or lengthened resting periods. The hair becomes thin and weak until it is finally lost and regrowth does not occur.
Next month's article will focus on additional causes of hair loss.