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Overview
Alopecia is the medical term for hair loss, and Alopecia areata is the term for hair loss from an isolated area. The patchy loss of hair from the head can have a number of underlying causes including infectious, metabolic, autoimmune and nervous.
Drugs and Other Toxins
Toxic alopecia is the term for hair loss due to drugs or other toxins in the body. Chemotherapy patients, for example often experience a type of toxic alopecia. If you are on any medications or have any occupational toxin exposure, ask your doctor if they could cause hair loss. An overdose of vitamin A or prescription Retin A can also cause hair loss.
Infections
Local infections in the scalp, such as a bacterial or fungal infections can cause hair loss. A dermatologist can often diagnose scalp infections by simply looking, but gently scraping the scalp and looking at the tissue under a microscope can identify fungal and bacterial elements. Performing a biopsy of the skin in the bald spot and having it examined by a histologist can also help identify more unusual skin disorders that may causes patchy hair loss. Serious systemic infections such as TB or syphilis can also cause hair loss. Also any prolonged high fever can cause hair loss.
Auto-Immune Diseases
Auto-immune diseases are disease where the body's own immune system attacks itself. Many cases of Alopecia are believed to be auto-immune driven. Alopecia totalis, where there is loss of hair throughout the entire body is believed to be an autoimmune phenomena. Antibodies to the body's own hair follicles have been demonstrated in many cases of Alopecia areata as well.
Metabolic Disorders
Metabolic and hormonal disorders, particularly hypothyroidism can cause hair loss. Hypothyroidism frequently causes dry skin, skin rashes, brittle fingernails and dry frizzy hair. Hair loss can also be associated with thyroid disease. A simple blood test can identify thyroid and other metabolic disorders.
Trichotillomania
Trichotillomania is a disorder where people may pull out their own hair one strand at a time. This is often a nervous habit and people may not even be aware that they are doing this. The hair loss is usually toward the front of the head, an area easy to reach with the hands. A hallmark of trichotillomania is the presence of new hairs in the bald spot. Because there is no actual disease or problem with hair growth, the pulled hairs grow right back and tiny new growth is evidence.
