Osteoporosis

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Osteoporosis, bone condition characterized by a decrease in mass, resulting in bones that are more porous and more easily fractured than normal bones. Fractures of the wrist, spine, and hip are most common; however, all bones can be affected. White females are the most susceptible, but other risk factors include low calcium intake; inadequate physical activity; certain drugs, such as corticosteroids, and a family history of the disease.

The most common form of the disease, primary osteoporosis, includes postmenopausal (see Menopause), or estrogen-deficient, osteoporosis (Type I), which is observed in women whose ovaries have ceased to produce the hormone estrogen; age-related osteoporosis (Type II), which affects those over the age of 70; and idiopathic osteoporosis, a rare disorder of unknown cause that affects premenopausal women and men who are middle-aged or younger. Secondary osteoporosis may be caused by bone disuse as a result of paralysis or other conditions, including weightlessness in space; endocrine and nutritional disorders, including anorexia nervosa; specific disease processes; and certain drug therapies.

Prevention and treatment of osteoporosis include synthetic estrogen or progestin therapy or both for postmenopausal women, intake of calcium and other nutrients, weight-bearing exercise, and drugs such as calcitonin and alendronate sodium, a nonhormonal treatment for osteoporosis.

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