Hair disorders can present as either hair loss or excessive hair growth. Hair loss may refer to excessive shedding or baldness (or both). Balding can be localized or diffuse, scarring, or non-scarring. Increased hair can be due to hormonal factors (hirsutism) or non-hormonal (hypertrichosis.
To better understand hair disorders one needs to know the cycle of hair growth. Hair grows from the follicle or root underneath the scalp skin. It goes through 4 stages called anagen (growing stage-80-90% of hairs, lasting for 2-6 years for scalp hair), catagen(regression stage), telogen(resting stage 10-15% of last for approximately 3 months) and exogen(new hair phase-old hair sheds about 50-150 a day, new hairs grows). Every hair on the scalp is at a different stage of the growth cycle. The rate of hair growth per day is about 1.25 cm per month.
Some of the common hair disorders are mentioned below.
Diffuse Alopecia (Hair Loss)
Androgenetic alopecia is the most common form of hair loss. This disorder occurs in both males and females, also known as male-pattern or female-pattern hair loss. This type of hair loss might be associated with other medical problems. In men hair loss begins above the temples and progresses to involve the crown. In women, hair becomes thinner all over the head.
Telogen effluvium is the second most common form of hair loss. It is marked by a significant decrease in scalp hair. This condition is related to diffuse alopecia, and diagnosis can be made once other hair disorders have been ruled out. Telogen effluvium may follow two or three months after childbirth, sudden weight loss, blood loss, fever or stress.
Diffuse alopecia is hair loss from the scalp that can also be caused by infections, nutritional deficiencies, imbalance of hormones or other physical or emotional stressors, alopecia areata, or even medications.
Alopecia areata is the most common cause of one or more areas of localized baldness on the scalp and other hair-bearing areas. It is an autoimmune skin disease and is more common in those affected by, or with a family history of another autoimmune disease. Although the onset may be at any age, it most often starts in childhood or young adult life.
Inflammatory Hair Loss
These disorders may result in scarring (cicatricial alopecia) in which there are shiny pale skin and reduced or absent follicular orifices. Some of the common ones include
Lichen planopilaris is a rare inflammatory condition that leads to permanent hair loss, mainly on the scalp. It is usually seen in young adult women though it may also affect men. The cause of this hair disorder is unknown.
Frontal fibrosing alopecia is a hair disorder that typically affects women over the age of 50. It causes even hair loss on the front and sides of the scalp, as well as the loss of eyebrows. Skin in the affected area usually looks normal but maybe pale, shiny, or mildly scarred.
Folliculitis decalvans can affect hair on any part of the body. Round oval patches of hair loss occur with pustules that surround hair follicles. As hair is shed, follicles are destroyed and scarring results. It affects both men and women and may begin during adolescence or at any in adulthood. Dissecting cellulitis is a very rare condition. Pustules develop over the scalp and permanent hair loss results. Infections including fungal infections left untreated can result in permanent hair loss.
If you suspect you have any of the above mentioned hair disorders you must see your dermatologist.
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