HAIR LOSS: WHAT IS HAIR LOSS AND WHAT CAUSES HAIR LOSS

Hair grows everywhere on the human skin except on the palms of our hands and the soles of our feet, but many hairs are so fine they're virtually invisible. Hair is made up of a protein called keratin that is produced in hair follicles in the outer layer of skin. As follicles produce new hair cells, old cells are being pushed out through the surface of the skin at the rate of about six inches a year. The hair you can see is actually a string of dead keratin cells. The average adult head has about 100,000 to 150,000 hairs and loses between 100 to 150 of them each day.

At any one time, about 90% of the hair on a person's scalp is growing. Each follicle has its own life cycle that can be influenced by age, disease, and a wide variety of other factors. This life cycle [follicle life cycle] is divided into three phases:

v  Anagen -- active hair growth that lasts between two to six years

v  Catagen -- transitional hair growth that lasts two to three weeks

v  Telogen -- resting phase that lasts about two to three months; at the end of the resting phase the hair is shed and a new hair replaces it and the growing cycle starts again.

Each one of us has a different chance of losing our hair, as we grow old. Our genetic predispositions, diet, stress level and hair care habits differ from one another and this can affect how we lose our hair. There are many causes of scalp hair loss, and they do differ in men and women.  Human hair naturally grows in three phases [as stated earlier] 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. Normally, about 10% of the scalp hairs are in the resting or Telogen phase at any time. These hairs are not growing and are getting prepared for cyclic shedding.

 In general, most hair loss is not associated with systemic or internal disease, nor is poor diet a frequent factor. Notably, 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 (CBC), on people who have ordinary hair loss are usually normal, it is important to exclude underlying causes in sudden or severe hair loss. If you are concerned about some other underlying health issues, you may start by seeing your family physician, internist, or gynecologist for basic health screening.

TYPES OF HAIR LOSS

• Involutional Alopecia: This is a natural condition in which the hair gradually thins with age. More hair follicles go into the resting phase, and the remaining hairs become shorter and less in number.
• Androgenic Alopecia : This is a genetic condition that can affect both men and women. Men with this condition, called male pattern baldness, can begin suffering hair loss as early as their teens or early 20's. It's characterized by a receding hairline and gradual disappearance of hair from the crown and frontal scalp. Women with this condition, called female pattern baldness, don't experience noticeable thinning until their 40's or later. Women experience a general thinning over the entire scalp with the most extensive hair loss at the crown [research has shown that up to 40% of women are affected by androgenic alopecia].

• Alopecia Areata: Often starts suddenly and causes patchy hair loss in children and young adults. This condition may result in complete baldness (alopecia totalis). But in about 90% of people with the condition, the hair returns within a few years.  
• Alopecia Universalis : This causes all body hair to fall out, including the eyebrows, eyelashes, and pubic hair.

• Trichotillomania: This is seen most frequently in children, is a psychological disorder in which a person pulls out one's own hair.
•      Telogen Effluvium: This is temporary hair thinning over the scalp that occurs because of changes in the growth cycle of hair. A large number of hairs enter the resting phase at the same time, causing hair shedding and subsequent thinning.

WHAT CAUSES HAIR LOSS

Doctors don't know why certain hair follicles are programmed to have a shorter growth period than others. However, there are several factors believed to influence hair loss:

• Hormones: Abnormal levels of androgens (male hormones normally produced by both men and women) can result in hair loss.
• Genes: Definitely, genetics play a major role in our life, so it should be no surprise to anyone that they affect hair loss. Genetic predisposition affects both male and female pattern baldness.
• Stress, illness, and childbirth, can cause temporary hair loss. Ringworm caused by a fungal infection can also cause hair loss.
• Drugs, including chemotherapy drugs used in cancer treatment, blood thinners, and beta-adrenergic blockers used to control blood pressure, and birth control pills, can cause temporary hair loss.
• Burns, injuries, and X-rays can cause temporary hair loss. In such cases, normal hair growth usually returns once the injury heals.
• Autoimmune disease may cause alopecia areata. In alopecia areata, the immune system revs up for unknown reasons and affects the hair follicles. In most people with alopecia areata, the hair grows back, although it may temporarily be very fine and possibly a lighter color before normal coloration and thickness return.
• Cosmetic procedures, such as shampooing too often, perms, bleaching, and dyeing hair can contribute to overall hair thinning by making hair weak and brittle. Tight braiding, using rollers or hot curlers, and running hair picks through tight curls can also damage and break hair. However, these procedures don't cause baldness. In most instances hair grows back normally if the source of the problem is removed. Still, severe damage to the hair or scalp sometimes causes permanent bald patches.  
• Medical conditions. Thyroid disease, lupus, diabetes, iron deficiency, and anemia can cause hair loss, but when the underlying condition is treated the hair will return.
• Diet. A low-protein diet or severely calorie-restricted diet can also cause temporary hair loss.

Although many medications list "hair loss" among their potential side effects, drugs are also not overall common causes of thinning or lost hair. On the other hand, with cancer treatments and immune suppression medications including chemotherapy, hair loss is a very common side effect. Complete hair loss often occurs after a course of major chemotherapy for cancer. Hair usually re-grows after six to 12 months.