What are causes of hair loss?

There are many causes of scalp hair loss. This article will cover the common ones.

In general, most hair loss is not associated with systemic or internal disease, nor is poor diet a frequent factor. Thyroid disease can cause hair loss, but thyroid tests on people who have ordinary hair loss are usually normal. 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, hair loss is not uncommon.

One useful way to classify hair loss is by whether the loss is localized and patchy or whether it affects large areas or the whole scalp.

Patchy hair loss

Some conditions produce small areas of hair loss, while others affect large areas of the scalp. Common causes of patchy hair loss are

• alopecia areata (patches of baldness that usually grow back),



• traction alopecia (thinning from tight braids or ponytails),



• trichotillomania (the habit of twisting or pulling hair out),



• tinea capitis (fungal infection).

Alopecia areata

A common condition, alopecia areata usually starts as a single quarter-sized circle of perfectly smooth baldness. Alopecia patches usually regrow in three to six months without treatment. Sometimes, hair grows back in white. In another variant, alopecia can produce two or three bald patches. When these grow back, they may be replaced by others. 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 generally don't go on to lose hair all over the scalp. Alopecia can affect hair on other parts of the body, too -- for example, the beard.

Alopecia areata is considered an autoimmune condition, in which the body attacks itself (in this case its own hair follicles). Most alopecia patients, however, do not have systemic problems and need no medical tests. Alopecia is also often blamed on "stress," but in fact, it's usually the other way around: Having alopecia causes the stress, at least until people find out what it is.

Treatments for alopecia areata include injecting steroids into affected patches to stimulate hair growth. This is not practical for large areas. Other treatments, such as oral steroids or ultraviolet light therapy, are either toxic or impractical. In most mild cases, patients can comb over the affected areas. In more severe and chronic cases, some patients wear hairpieces; nowadays, some men shave their whole scalp now that this look has become fashionable.

Traction alopecia

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 pressure on hair roots. The sooner this is done the better, to avoid permanent damage.

Trichotillomania

This melodramatic name refers to the habit of pulling at hairs or twisting them, sometimes without realizing it. The scalp and eyelashes are often affected. Unlike alopecia areata patches, which are perfectly smooth, hair patches in trichotillomania show broken-off hairs. Treatment is entirely behavioral: You have to notice that you're doing it and then stop!

Tinea capitis (fungal infection)

Fungal infection of the scalp for the most part affects school-age children. Bald spots usually show broken-off hairs. Oral antibiotics are needed to penetrate the hair roots and cure the infection after which hair grows back.

Generalized (diffuse) hair loss

Common conditions in this category are

• telogen effluvium (rapid shedding after childbirth, fever, or sudden weight loss);



• androgenetic hair loss ("male-pattern baldness," "female-pattern baldness").

Telogen effluvium

Under normal conditions, scalp hairs live for about three years (the anagen, or growing, phase); they then enter the telogen, or resting, phase. During the three-month telogen period, the hair root shrivels up into a small white "club," then the hair falls out. It is therefore 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 hairs are then replaced by the body.

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. Normally, about 10% of scalp hairs are in the telogen phase.

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 (crash dieting),
• surgery.

None of these has to be life-threatening, nor does hair loss always follow them. (It can happen after one pregnancy but not the next.) But when the hair falls out, it's all over the place -- covering the pillow, clogging the drain, and so forth. Paradoxically, the more dramatic the hair loss, the better the prognosis, because when the body gets back into normal rhythm, most if not all of that hair comes back. No special treatment is needed. Normal shampooing can continue, because this only loosens hairs that were going to come out anyway.

Androgenetic alopecia ("male-pattern baldness," "female-pattern baldness")

Everyone loses hair, but men do it better -- faster, earlier, and more extensively.

Doctors refer to common baldness as "androegentic alopecia," which implies that a combination of hormones and heredity (genetics) is needed to develop the condition. (The male hormones involved are present in both men and women.)

Male-pattern baldness

Even men who never "go bald" thin out over the years. Unlike those with reversible telogen shedding, those with common male-pattern hair loss don't notice much hair coming out; they just see that it's not there anymore. Adolescent boys notice some receding near the temples as their hairlines change from the straight-across boys' pattern to the more "M-shaped" pattern of adult men. This normal development does not mean they are losing hair.

Male-pattern baldness

Some "myths" about male-pattern baldness

• You inherit baldness through your 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.



• Longer hair puts a strain on roots. They don't. And hats don't choke off the circulation to the scalp to cause hair loss either.



• Shampooing does not accelerate balding.
  
  
• "Poor circulation" does not cause hair loss, and massaging doesn't stop it.

What treatments are there for hair loss in men?

Many conditioners, shampoos, vitamins, and other products claim to help hair grow in some unspecified way. These are harmless but useless. To slow down hair loss, there are two basic options:

• Minoxidil (Rogaine): This topical application is available over the counter, no prescription is required. It works best on the crown, less on the frontal region. Available as a 2% solution, Rogaine may grow a little hair, but it's better at holding onto what's still there. There are few side effects with Rogaine. The main problem with this treatment is the need to keep applying it twice a day, and most men get tired of it after a while. In addition, minoxidil works less well on the front of the head, which is where baldness bothers most men. This drug also comes in a higher strength, 5%, which may be a bit more effective.



• Finasteride (Propecia): This is a lower-dose version of a drug that shrinks prostates in middle-aged men. Propecia is available by prescription and is taken once a day. Propecia does grow and thicken hair to some extent, but its main use is to keep hair that's still there. It's therefore best for men who still have enough hair to retain. One side effect is impotence, but this is no more common than it is in the general population and is reversible when the drug is stopped. Taking Propecia once a day is easier that applying minoxidil, but the prospect of taking a pill daily for years doesn't sit well with some men. There's also the cost, about $60/month, not reimbursed by most health insurers.

Minoxidil and Propecia are meant to be used indefinitely. Those who change their mind and stop are left where they would have been without them but no worse.

What other options do I have for hair loss?

Hairpieces, etc.

Among the time-honored ways to add hair temporarily are hairpieces or hair weaving, in which a mesh is attached to your remaining hair and artificial or human hair of similar color and texture is woven with existing hair. Quality varies considerably with price; also, hairpieces and weaves stretch, oxidize, and loosen.

Surgery

Surgical approaches include various versions of hair transplantation (taking hair from the back and putting it near the front) or scalp reduction (cutting away bald areas and stitching the rest together). Transplant procedures have improved greatly in recent years. They can produce much more attractive and natural-looking results than older methods that sometimes left a "checkerboard" look. Many transplant patients now take Propecia to keep what they've transplanted. When considering a hair transplant, check the surgeon's credentials and experience carefully.

Is hair loss in women different than men?

Female-pattern baldness

Women lose hair on an inherited (genetic) basis, too, but the female pattern is more diffuse, with less likelihood of the frontal hairline being lost. Although some women may notice hair thinning as early as their 20s, the pace of hair loss tends to be gradual, often taking years to become obvious to others. (It's common to hear women with what appear to have a full head of hair exclaim, "This is nothing...You should have seen how thick it used to be!")

Notions about baldness being inherited through the mother's family, just like stories about hats choking off follicles or long hair pulling on the roots, are just folklore.

Hair loss "myths" of special concern to women:

• Longer hair does not put a strain on roots.



• Shampooing does not accelerate hair loss; it just removes those that were ready to fall out anyway.



• Coloring, perming, and conditioning the hair do not usually cause hair loss. Styles that pull tight may cause some loss, but hair coloring and "chemicals" don't.

What treatments are there for hair loss in women?

• Ask your doctor about minoxidil (Rogaine). This is available over the counter and available in 2% and 5% concentrations. It's something of a nuisance to apply, but it helps conserve hair and may even grow some.



• Propecia is a drug that helps men retain their hair. It is unsafe for women of childbearing to take this drug or even handle tablets. (It is, however, safe for their husbands to take it while they are trying to become pregnant.) Propecia is safe for older women but not very effective; newer studies suggest that it might be somewhat helpful and may be worth considering.



• Surgical procedures like hair transplants can be useful for some women as well as men to "fill in" thinned-out areas.

REFERNCES:

Bolognia, Jean, Jorizzo, Joseph, and Rapini, Ronald. Dermatology. Philadelphia: Mosby Elsevier, 2008.

Last Editorial Review: 11/13/2009

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