Hair Loss Quiz: Test Your Medical IQ

Everyone loses some hair every day. Losing up to 100 hairs a day is normal and does not mean you are going bald. The scalp has some 100,000 hair follicles, most of which are producing hair at any moment in time.

It is a myth that baldness is inherited through a mother's male relatives. Actually, baldness can come from either side of the family, or both. Looking at your family can give you at best an educated guess about how you'll turn out.

Several health conditions, including thyroid disease and iron deficiency anemia, can cause hair loss. While thyroid blood tests and other lab tests, including a complete blood count, of people who have ordinary hair loss are usually normal, it is important to exclude underlying causes with sudden or severe hair loss.

If you are experiencing sudden or unexplained hair loss, it is best to visit a dermatologist. Dermatologists are doctors who specialize in problems of skin, hair, and nails and may provide more advanced diagnosis and treatment of hair thinning and loss.

Human hair naturally grows in three phases: anagen, catagen, and telogen. Anagen is the active or growing phase. Catagen is a fairly short phase of the natural hair cycle during which hairs begin to break down. Telogen is the resting phase. The hairs that are shed daily are often in the resting or late phase in the hair cycle.

Trichotillomania is the medical term for constant hair pulling or twisting. It is a disorder characterized by the repeated urge to pull out scalp hair, eyelashes, eyebrows, or other body hair. It is believed to be related to obsessive-compulsive disorder (OCD). Treatments may include cognitive-behavior therapy and prescription medications. From tricho-, hair + Greek till (ein) to pluck, pull out + -o- + -mania.

Alopecia areata is an autoimmune condition in which the body attacks its own hair follicles. Alopecia areata usually starts as a single quarter-sized circle of perfectly smooth baldness. Patches usually regrow in three to six months without treatment. Sometimes, hair grows back in white. Alopecia can also produce two or three bald patches. When these grow back, other bald patches may replace them. The most extensive form is called alopecia totalis, in which the entire scalp goes bald. It's important to emphasize that patients who have localized hair loss don't typically lose hair all over the scalp. Alopecia can affect hair on other parts of the body, too -- for example, the beard or eyebrows.

Traction alopecia refers to a small or localized hair loss area caused by repetitive or persistent pulling or force on hair roots. Tight braids and ponytails can pull hard enough on hairs to make them fall out. If this happens, it's best to choose hairstyles that put less strain on hair roots. The sooner this is done the better to avoid permanent damage.

Under normal conditions, scalp hairs live for about three years. This period is referred to as the anagen, or growing, phase. They subsequently enter the telogen, or resting, phase.

Normally, about 10% of scalp hairs are in the telogen phase. During this three-month period, the hair root shrivels up into a small white "club," then the hair falls out. It is normal to lose about 100 hairs every day, more of them on days when shampooing loosens the hairs that are ready to fall out. The body then replaces the hairs. Sometimes people worried about losing their hair start noticing hairs on their pillow or in the sink, not realizing that they've always been there. A close look at these will usually reveal the white club at the end, showing that these hairs were already dead!

There are several circumstances that produce a "shock to the system" that alters the hair growth rhythm. As a result, as much as 30%-40% of the hairs can cycle into telogen. Three months later, hairs come out in a massive shedding (effluvium), especially near the front of the scalp. These include childbirth, high fever, sudden weight loss from crash dieting, surgery, severe illness, and stressors such as a loss, death, or divorce.

Androgenic alopecia is the medical term for "male pattern baldness." This type of hair loss is often attributed to genetic predisposition and family history. Traditionally, this was originally described only in men, but we now know it is seen in both men and women. The hair loss in men is often faster, earlier onset, and more extensive.

In general, most hair loss is not associated with systemic or internal disease, nor is poor diet a frequent factor. Often, hair simply thins as a result of predetermined genetic factors, family history, and the overall aging process. Many men and women may notice a mild and often normal thinning of hair in their thirties and forties. Other times, normal life variations including temporary severe stress, nutritional changes, and hormonal changes like those in pregnancy, puberty, and menopause cause hair loss that is reversible.

Shampooing does not accelerate hair loss; it just removes the hairs that were ready to fall out anyway. Coloring, perming, and conditioning the hair do not usually cause hair loss. Burns or severe processing may cause hair loss and breakage. Styles that pull tight may cause some loss, but hair coloring and chemicals usually don't.