Hair Loss

Definition

Hair loss, or alopecia, is total or partial baldness caused by hormonal changes or physical or mental stress.

Description

Hair loss occurs for many reasons. Some causes, such as hormonal changes, are considered natural, while others signal serious health problems. Some conditions are confined to the scalp, while others reflect disease processes throughout the body.

Causes & symptoms

Androgenetic alopecia occurs in both men and women, and is considered normal in adult males. Also known as male pattern baldness, it is easily recognized by the distribution of hair loss over the top and front of the head (leaving a horseshoe pattern of hair) and by the healthy condition of the scalp. Women with androgenetic alopecia experience hair thinning, particularly over the top of the scalp. The disorder is thought to be caused by a genetic predisposition that triggers the production of certain enzymes that convert testosterone into the hormone dihydrotestosterone (DHT). DHT is known to shrink hair follicles, and can cause partial or complete hair loss.

Alopecia areata and alopecia circumscripta refer to hair loss conditions that can be patchy or extend to complete baldness. The exact cause of alopecia areata is unknown, but it is thought to be triggered by an immune system disorder.

Oftentimes, conditions affecting the skin of the scalp will result in hair loss. The first clue to the specific cause is the pattern of hair loss, whether it be complete baldness (alopecia capitis totalis), patchy bald spots, thinning, or hair loss confined to certain areas. Also a factor is the condition of the hair and the scalp beneath it. Sometimes only the hair is affected; sometimes the skin is visibly diseased as well.

Fungal infections of the scalp usually cause patchy hair loss. The fungus, similar to the ones that cause athlete's foot and ringworm, often glows under ultraviolet light.

Complete hair loss is a common result of cancer chemotherapy, due to the toxicity of the drugs used. Placing a tourniquet around the skull just above the ears during the intravenous infusion of the drugs may reduce or eliminate hair loss by preventing the drugs from reaching the scalp. However, this technique may not be recommended in the treatment of certain types of cancer. An investigational topical gel that may prevent chemotherapy-related hair loss, known as GW 8510, was in clinical trials as of April 2000.

Systemic diseases often affect hair growth either selectively or by altering the skin of the scalp. One example is thyroid disorders. Hyperthyroidism (too much thyroid hormone) causes hair to become thin and fine. Hypothyroidism (too little thyroid hormone) thickens both hair and skin. Several autoimmune diseases also affect the skin and potentially the hair, notably lupus erythematosus.

Hair loss can also be caused by trichotillomania, a mental disorder or compulsion that causes a person to pull out his/her own hair. In some individuals severe mental or physical stress can cause hair loss, including major surgery or illness, significant life changes (i.e., divorce, death of a loved one), and drastic dietary changes. This type of hair loss is called Telogen effluvium, and is the second most common type of hair loss.

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Author Info: Paula Ford-Martin, Teresa G. Odle, The Gale Group Inc., Gale, Detroit, Gale Encyclopedia of Alternative Medicine, 2005

This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.