This happened to the TV presenter in the United Kingdom, Gail Porter...

While most hair loss in men is caused by male pattern baldness that is a simple genetic condition there are many different types of hair loss that are rarer and cannot be cured by the use of hair loss drugs like Propecia. The clinical name for male pattern baldness is Androgenetic Alopecia and in fact it is not only restricted to men but in some rare cases women can suffer from it too.

Another type of hair loss is Alopecia aerate which occurs when hair is lost on the scalp in small circular patches and this is caused by an auto-immune response where the body gets confused and actually attacks its own hair follicles. In a lot of cases this hair loss is short lived and hair grows back when the body readjusts itself.

Alopecia Totalis is a similar autoimmune disease but is a more extreme effect when all the hair on the scalp is attacked and can lead to complete baldness. The most extreme form of this autoimmune condition which is extremely rare is called alopecia universalis.  Recently the most famous case of this happened to the TV presenter in the United Kingdom, Gail Porter, in which she lost every single hair on her body including her eyelashes and eyebrows.

Other types of hair loss include Traction Alopecia which is caused by chronic trauma to hair follicles from extreme braiding or pulling of the hair. This form of hair loss usually goes away when the hair his left alone and the trauma is stopped. Scarring Alopecia occurs when hair follicles are completely destroyed by skin diseases like lupus and the skin tissue is replaced with scar tissue. Telogen effluvium can cause temporary hair loss to and often occurs in women after they have given birth or when they take birth control medication which interferes with hormonal patterns.

Lastly but by no means least Trichotillomania is the very rare condition when people literally pull out their hair from a nervous habit. Stress and anxiety can cause adults and children to twist their hair round their fingers and to pull it out as a means of relieving stress. This sort of hair loss is usually cured with special counselling and anti-anxiety medication.