Androgenic alopecia (male pattern baldness)
Androgenetic alopecia is undoubtedly the most common cause of hair loss. It is progressive patterned hair loss in which there occurs androgen mediated conversion of susceptible terminal hairs into vellus hairs in genetically predisposed individuals. It affects at least 50% of men by the age of 50 years and 50% women by the age of 60 years. It is more obvious in men, and often manifests itself a decade earlier in men than in women. Although the condition is so frequent that it is sometimes considered a physiological sign of aging, it causes considerable discomfort to patients and has been proven to impair their quality of life. It presents in young men with frontal receding followed by thinning of the crown and there is often a positive family history.
Alopecia areata is an immune-mediated type of hair loss. It is associated with other organ-specific autoimmune diseases. It presents in childhood or young adults with patches of baldness. These may regrow to be followed by new patches of hair loss. Occasionally all of the scalp hair is lost (alopecia totalis) and rarely all body hair is lost (alopecia universalis). The nails may be pitted or roughened.
Female Pattern Alopecia
In women, the signs of androgenetic alopecia (AGA) are more subtle and vary considerably from male AGA. An early sign is a widened central parting. The patient may note that her "ponytail" is much thinner. On closer examination with a lens, the hair unit number is reduced from the usual three hairs per unit to two or even a single hair per unit. Moreover, small lacunar areas (4–6 mm) of partial or complete alopecia occur in areas of diffuse thinning. There are two peaks in the age of onset of FPA. The first peak occurs in the third decade and the second in the fifth decade; those with an earlier age of onset have more severe hair loss.
It may be associated with polycystic ovary syndrome, hirsuitism, acne. In most patients with FPA, no hormonal imbalances are found.
Telogen effluvium refers to the pattern of diffuse hair loss that occurs some 3 months after pregnancy or a severe illness. It occurs because 'stress' puts all the hairs into the telogen phase of hair shedding at the same time. The stressful circumstances that can result in telogen effluvium include febrile states like malaria, typhoid or tuberculosis, difficult labor, major accident or surgical trauma, hemorrhage, severe emotional stress, starvation, crash dieting, leukemia, lymphoma, and severe liver or kidney dysfunction. Telogen effluvium has also been observed occurring after allergic contact dermatitis of scalp to hair dyes.
The hairs regrow within six months but in severe cases regrowth may be incomplete. Oral multivitamin supplements may be given.