Alopecia universalis

Alopecia universalis is the most severe form of alopecia areata, an inflammatory disease of the hair follicle, which is characterized by a complete loss of hair of the scalp and all the hair-bearing areas of the body.
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Alopecia totalis

Alopecia totalis is a form of alopecia areata, an inflammatory disease of the hair follicle, characterized by a complete loss of hair of the entire scalp which becomes glabrous.
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Alopecia areata

Alopecia areata is an autoimmune disease that affects almost 2% of the US population, including more than five million people in the United States alone. In alopecia areata, the affected hair follicles are mistakenly attacked by a person's own immune system (white blood cells), resulting in the arrest of the hair growth stage. Alopecia areata usually starts with one or more small, round, smooth bald patches on the scalp and can progress to total scalp hair loss (alopecia totalis) or complete body hair loss (alopecia universalis). Any hair-bearing site on the body can be affected by alopecia areata. Hair loss can often occur without any accompanying symptoms.
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Alopecia areata

Source: National Institute of Arthritis and Musculoskeletal and Skin Diseases

What Causes It?

In alopecia areata, immune system cells called white blood cells attack the rapidly growing cells in the hair follicles. The affected hair follicles become small and drastically slow down hair production. Fortunately, the stem cells that continuously supply the follicle with new cells do not seem to be targeted. So the follicle always has the potential to regrow hair.
Scientists do not know exactly why the hair follicles undergo these changes, but they suspect that a combination of genes may predispose some people to the disease. In those who are genetically predisposed, some type of trigger—perhaps a virus or something in the person’s environment—brings on the attack against the hair follicles.

Hair loss

Hair loss is also called: Alopecia

You lose up to 100 hairs from your scalp every day. That's normal, and in most people, those hairs grow back. But many men -- and some women -- lose hair as they grow older. You can also lose your hair if you have certain diseases, such as thyroid problems, diabetes, or lupus. If you take certain medicines or have chemotherapy for cancer, you may also lose your hair. Other causes are stress, a low protein diet, a family history, or poor nutrition.

Treatment for hair loss depends on the cause. In some cases, treating the underlying cause will correct the problem. Other treatments include medicines and hair restoration.
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Hair loss / Alopecia

Author: Dr Bryan Cho University of California SF 2009-01-22

Common Causes of Hair Loss from the Scalp. Non Scarring Alopecias: A brief review of common causes of hair loss in men and women.

Hair loss, or alopecia, is a common and often emotionally distressing condition. Genetic predisposition, disease and improper hair care can all contribute to hair loss. They do so by increasing the rate of hair shedding (hair coming out by the root) or by increasing hair fragility leading to hair that can be broken by even minor trauma. 

Depending on the cause, there are a number of treatments for scalp hair loss with varying degrees of effectiveness and patient satisfaction. This knol will discuss the typical hair cycle, as well as the various types of scalp hair loss and their associated treatments.