Going bald for no apparent reason is an affliction confined largely to men. It is usually hereditary and is almost always gradual, starting at the front of the scalp, on either the side or in a circular area on top.
Both men and women lose some hair as they grow older. If hair loss is sudden however, it may be a symptom of disease, in particular a hormonal disturbance. The most common reason is an over- or underactive thyroid gland. If this is successfully treated, the hair will grow back again. Certain other glandular diseases, especially those involving the pituitary, have similar effects. Hormonal fluctuations may occur after pregnancy and lead to hair loss, but the system will normally readjust quite quickly.
Any serious illness, especially if it is accompanied by a fever, may lead to hair loss from the whole body, not just the scalp. Drugs used in treating illness, especially cancer, can also cause the hair to fall out, as can radiation therapy. When the treatment is stopped the hair usually grows back. Too much vitamin A can lead to hair loss. You may also lose your hair if you have a sudden and excessive loss of weight – sufferers of anorexia nervosa frequently find their hair falling out and may go bald.
Children often lose small areas of hair if they have ringworm, a highly infectious fungal infection which circulates throughout the community from time to time.