Spot baldness, also known as alopecia areata, can be caused by many different medical conditions, as well as injuries. Hair loss may be hereditary in some cases, but the only way to determine the cause of hair loss is to see a doctor for a physical examination of the scalp. Your physician may order additional tests if necessary.

Scalp Damage

Damage to the scalp causes damage to the follicles, which results in permanent hair loss; this is called cicatricial alopecia (scarring alopecia). It appears as round, patchy, inflamed, bald areas on the scalp.

Scalp Infections

The most common cause of balding due to scalp infection is tinea capitis (scalp ringworm). This fungal infection can be picked up from using infected combs, hats or clothing. Tinea capitis appears as patchy, bald areas on the scalp with little black spots. There may also be itching and inflammation.

Traction

Constant pulling of scalp hair, as in those who wear tight braids, causes traction alopecia. This constant pulling causes damage to the hair follicle, which over time results in bald patches. Traction alopecia usually causes thinning and baldness from the hairline.

Self-Inflicted

Trichotillomania is a type of self-inflicted alopecia. People with this condition cause balding by pulling out their hair. Researchers aren't sure why this happens, but they have found links to stress.

Hormonal Disorders

People with hormonal disorders such as diabetes and polycystic ovary syndrome often have thinning hair. In some cases, the thinning becomes baldness. These areas of thinning or balding can be controlled by androgens (male hormone). Hair regrowth may be possible unless the follicles are damaged.

Source:

Medline Plus: Alopecia Areata

Medline Plus: Tinea Capitis

Traction Alopecia