Hypertrichosis is an excessive hair disorder featuring abnormal hair density and length as compared to normal growth expected for the individuals's age, ethnicity and sex. A diagnosis of hypertrichosis does not imply any particular hair distribution. Except in very rare cases there is no androgen hormone involvement in cases of hypertrichosis. In contrast, excessive hair growth diagnosed as hirsutism in women involves androgen hormone activity and a male pattern of hair growth on the chin, upper lip, and other areas where men have terminal hair growth.

Causes Of Hypertrichosis

Hypertrichosis is the term used to describe excess hair growth in any part of the body as compared to that of a normal person of the same race, age or sex excluding androgen induced growth.

Hypertrichosis is usually categorized as either generalized or localized but age of onset and the site of growth can also be a basis of classification. Each of the generalized and localized types is further sub-divided into congenital and acquired sub-types. Hypertrichosis involves lanugo, vellus and terminal hairs.

Hypertrichosis is the term used to describe excess hair growth in any part of the body as compared to that of a normal person of the same race, age or sex excluding androgen induced growth.

Hypertrichosis is usually categorized as either generalized or localized but age of onset and the site of growth can also be a basis of classification. Each of the generalized and localized types is further sub-divided into congenital and acquired sub-types. Hypertrichosis involves lanugo, vellus and terminal hairs.

Generalized Acquired Hypertrichosis / GAH

Generalized acquired hypertrichosis (GAH) conditions are caused by drug intake and by underlying abnormalities. GAH induced by drugs is more common and needs to be separated from other forms of generalized hypertrichosis.

Drug induced GAH

Phenytoin, cyclosporine and minoxidil are the better known among the several drugs that cause significant generalized hypertrichosis.

Phenytoin induces hypertrichosis three months or so after its intake. Hypertrichosis induced by phenytoin affects women more than men and is more prominent on the extensor aspects of the limbs and less on the face and trunk.

60% of patients treated with cyclosporine develop hypertrichosis within six months. Thick pigmented hairs appear on the face, trunk and limbs.

Oral minoxidil and, to a lesser extent, topical minoxidil cause hypertrichosis after a few weeks of therapy. Face and extremities are the affected areas.

The hair growth disappears within a year on discontinuation of these drugs. Time for the condition to resolve depends on the hair cycling characteristics of the affected area.

GAH caused by underlying abnormalities

Exposure to chemicals, such as hexachlorobenzene induces hepatic porphyria and associated hypertrichosis.

Head injuries often result in hypertrichosis. Earlier the condition was attributed to phenytoin drug intake by the patient but later hypertrichosis was found even in those with head injuries but who were not on the drug. This explains why some lose their hair and some do not after discontinuation of this drug.

Malnutrition and anorexia nervosa causes hypertrichosis on the limbs and trunks of some people. Hypertrichosis may also occur in children with celiac disease and in dieting women when carbohydrates are omitted for prolonged periods of time.

Quite often, AIDS infection causes localized hypertrichosis, but a generalized form has also been observed. The mechanism for the development of hypertrichosis is unknown, but probably there are several contributing factors related to malnutrition, metabolic changes, immunological deregulation and drug intake.

Hair Removal Treatments Of Hypertrichosis

Excessive hair disorders like hypertrichosis give affected people a very repulsive appearance. This ugly appearance makes people shun those affected producing serious emotional problems in them.

Cosmetic treatments

Currently the common cosmetic treatments available are shaving, plucking, epilation, chemical depilation, electrolysis and laser application.

Shaving: Shaving is the simplest but most tedious since to retain the cosmetic appearance shaving has to be done frequently, perhaps daily. Moreover, women oppose such masculine rituals. There is also the risk of getting pseudofolliculitis due to shaving of kinky hairs.

Plucking: Plucking involves uprooting the hairs by tweezers. It produces a more attractive appearance but is slow and painful and impractical for large areas. Also, plucking encourages hair growth by changing telogen to anagen. Repeated plucking can produce disorders, such as, erythema, pigmentation, folliculitis and scarring. It is suitable for small sites

Epilation: Epilation, or waxing, is glorified plucking, where large numbers of hairs are uprooted at one go. The site is covered with low melting wax, allowed to solidify and then swiftly pulled off plucking the hairs sticking to it. The cosmetic effect lasts longer for about a month but the treatment is painful. Also, breaking of anagen hairs may cause folliculitis. Sometimes patients have allergic reactions to the wax or whatever adhesive is used. Plucking is best when the hairs are at least 1mm. long. It is too painful for children.

Depilation: Chemical depilatories are easy to use and produce excellent results that can last more than two weeks. They are mostly variants of thioglycolates used for perming hair and work in the same way to reduce the hair mass to a soft jelly.

Laser Hair Removal

Laser hair removal systems are currently widely used for long-term hair removal. The need to have a fast and non-invasive treatment method led to the development of this treatment.

All laser treatment systems use the principle of selective photothermolysis where a selected chromophore is targeted by the laser to produce the heat that destroys the follicle. Therefore deep penetrating wavelengths in the range of 600 ? 1100 nano meters (nm) are used. Care is taken to limit skin damage by restricting damage to the target area. This is done by ensuring enough laser absorption by the target and using a pulse rate shorter than the thermal relaxation time of the target.

The systems differ in the parameters like wavelength, pulse duration, fluence, spot size and repetition rate and in the cooling system used. The cooling device reduces heat conduction limiting skin damage and pain. The selection of these parameters is important for getting the ideal laser for an individual.