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Osteoporosis +@s-tE-O-pu-!rO-sus

By Marcy B. Bolster, MD

Osteoporosis is a condition in which a decrease in the density of bones weakens the bones, making fractures likely.

  • Aging, estrogen deficiency, low vitamin D or calcium intake, and certain disorders can decrease the amounts of the components that maintain bone density and strength.

  • Fractures, particularly of the back, hip, or wrist, can occur with little or no force.

  • Some people never develop symptoms, whereas others develop severe sudden pain or gradually develop aching bone pain and deformities.

  • Doctors diagnose people at risk by testing their bone density.

  • Osteoporosis can be prevented and treated by managing risk factors, ensuring adequate calcium and vitamin D intake, engaging in weight-bearing exercise, and taking bisphosphonates or other drugs.

Bones contain minerals, including calcium and phosphorus, which make them hard and dense. To maintain bone density, the body requires an adequate supply of calcium and other minerals and must produce the proper amounts of several hormones, such as parathyroid hormone, growth hormone, calcitonin , estrogen , and testosterone . An adequate supply of vitamin D is also needed to absorb calcium from food and incorporate it into bones. Vitamin D is absorbed from the diet and also manufactured in the skin using sunlight (see Vitamin D).

So that bones can adjust to the changing demands placed on them, they are continuously broken down and reformed, or remodeled (see Bones). In this process, small areas of bone tissue are removed and new bone tissue is deposited. This process is continuous. Remodeling affects the shape and density of the bones. In youth, the bones grow in width and length as the body grows. In later life, bones may sometimes enlarge in width but do not continue to grow longer.

Loss of Bone Density in Women

In women, bone density (or mass) progressively increases until about age 30, when bones are at their strongest. After that, bone density gradually decreases. The rate of bone loss accelerates after menopause, which occurs on average around age 51.

Because more bone is formed than is broken down in the young adult years, bones progressively increase in density until about age 30, when they are at their strongest. After that, as breakdown exceeds formation, bones slowly decrease in density. If the body is unable to maintain an adequate amount of bone formation, bones continue to lose density and may become increasingly fragile, eventually resulting in osteoporosis.

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