How is hair loss classified?

There are numerous ways to classify hair loss. One useful way has been to classify hair loss by whether the loss is localized (small area) and patchy or whether it affects large areas or the whole scalp (diffuse). Other medical classifications for hair loss include scarring versus non-scarring hair loss and are beyond the scope of this article.

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 (small circular or coin size patches of scalp baldness that usually grow back within months),
traction alopecia (thinning from tight braids or ponytails),
trichotillomania (the habit of twisting or pulling hair out),
and tinea capitis (fungal infection).  

What is 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 or eyebrow.

Alopecia areata is generally 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. While alopecia areata has frequently been blamed on "stress," in fact, it may be the other way around; that is, having alopecia may cause stress.

Treatments for alopecia areata include injecting small amounts of steroids like triamcinolone into affected patches to stimulate hair growth. Although localized injections may not be practical for large areas, often this is a very effective treatment in helping the hairs return sooner. Other treatments such as oral steroids, immunosuppressives, or ultraviolet light therapy are available for more widespread or severe cases but may be impractical for some because of potential side effects or risks. In most mild cases, patients can easily cover up or 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.