osteoporosis

Disease in which the bone substance becomes porous and brittle. It is common in older people, affecting more women than men. It may be treated with calcium supplements and etidronate. Approximately 1.7 million people worldwide, mostly women, suffer hip fractures, mainly due to osteoporosis. A single gene was discovered in 1993 to have a major influence on bone thinning.

Osteoporosis may occur in women whose ovaries have been removed, unless hormone-replacement therapy (HRT) is instituted; it may also occur in Cushing's syndrome and as a side effect of long-term treatment with corticosteroids. Early menopause in women, childlessness, small body build, lack of exercise, heavy drinking, smoking, and hereditary factors may be contributory factors.

Osteoporosis may also be seen in the bones of a young person whose limb has been immobilized.