Hair Loss and Its Causes

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The loss of scalp hair in adults can be categorized in several ways. Each method of categorization can be useful for diagnosis of the cause of hair loss and in planning of treatment.

To learn about the various treatments available for hair loss, see Hair Loss Treatments.

Some of the categories for hair loss include:

Association with Underlying Disease

• Hair loss has no association with underlying disease. Androgenetic alopecia falls into this category; it is hair loss due to a genetic predisposition.
  
  
  
• Hair loss is a sign or symptom of underlying disease such as hypothyroidism, cystic ovaries, lupus erythematosus. Treatment of the underlying disease may also treat the hair loss.

Pathophysiologic Hair Loss Categories

• Abnormalities of hair production. Androgenetic alopecia falls into this category.
• Hair shaft abnormalities.
• Abnormalities of hair cycling. The normal cycle of anagen-catagen-telogen is disrupted.
• Destruction of hair follicles. Disease or scalp injury may destroy hair follicles.

Scarring and Non-Scarring Hair Loss
Scarring hair loss is hair loss due to physical, thermal or chemical damage to the scalp that results of destruction of hair follicles and scarring of scalp skin. Common causes of scalp injury and scarring are: automobile accidents; long-term physical damage caused by corn-rowing or tight braiding of hair; chemical burns from home-made hair straightening, curling or coloring products; scalp burns; and, compulsive hair plucking (trichotillomania).

Male-Pattern and Female-Pattern Baldness (Androgenetic Alopecia)
Androgenetic alopecia-hair loss that "runs in the family" due to an inherited predisposition (see Hair Science: How and Why Hair Grows) was until recent decades believed to be restricted to males. While it was recognized that many women experienced thinning hair in adulthood, androgenetic alopecia was not considered to be a cause. Women also may have resisted the idea that a woman could "go bald".

It is now scientifically well documented that both men and women can experience hair loss due to androgenetic alopecia. The typical patterns of hair loss due to androgenetic alopecia are quite different in men and in women, however; the difference in hair-loss patterns may also have made it difficult to accept androgenetic alopecia as a cause of female hair loss.

The typical male patterns of androgenetic alopecia are illustrated in the Hamilton-Norwood classification, shown here:

Female pattern androgenetic alopecia tends to be a diffuse pattern of hair loss. A typical female hair loss pattern is the "Christmas tree" pattern of progressive hair loss from front to back on the scalp:

For more information on hair loss in women, visit the ISHRS website under Female Hair Loss & Pattern Baldness .

Androgenetic alopecia is the most prevalent cause of hair loss in adults. It is not the only cause. Other causes range from the very rare to the quite common. No cause can be eliminated in an individual person without a full diagnostic examination by a physician who specializes in diagnosis and treatment of hair loss.

For detailed information about all causes and treatments of hair loss, see:

International Society of Hair Restoration Surgery - a non-profit medical association devoted to the advancement of hair restoration. It is an unbiased source of information on hair loss, and medical and surgical hair restoration options.

American Academy of Dermatology - a non-profit medical association devoted to all aspects of dermatology - skin, hair, and nails.