Osteoporosis is a disease that thins and weakens bones to the point where they break easily — especially bones in the hip, backbone (spine), and wrist. Osteoporosis is called the "silent disease" — you may not notice any changes until a bone breaks. But your bones have been losing strength over many years.

Bone is living tissue. To keep bones strong, the body is always breaking down old bone and replacing it with new tissue. As people enter their 40's and 50's, more bone is broken down than is replaced. A close look at the inside of bone would show something that looks like a honeycomb. When you have osteoporosis, the spaces in this honeycomb grow larger. The outer shell of your bones also gets thinner. All this makes your bones weaker.

Who Gets Osteoporosis?

Ten million Americans have osteoporosis, and eight million of them are women. About 34 million more have osteopenia. This means they don't have osteoporosis yet, but have lost enough bone to make them more likely to get it. One in two women and one in eight men over age 50 will have an osteoporosis-related fracture during their lives. White and Asian women are most likely to get osteoporosis. Other women at great risk include those who:

· have a family history of the disease,

· have not gotten enough calcium throughout their lives,

· had an early menopause,

· had surgery to remove their ovaries,

· had extended bed rest,

· used certain medicines for a long time, or

· have small body frames.

The risk of osteoporosis grows as you get older. Bone loss may begin slowly in some people when they are in their late thirties. At the time of menopause women may lose bone quickly for several years. Then the loss may continue but more slowly. As men age, they do not have the same kinds of striking hormone changes as women do in mid-life because they do not have a menopause. In men the loss of bone mass occurs more slowly. But, by age 65 or 70 men and women are losing bone at the same rate.

How Do I Know If I Am Losing Bone?

Losing height or having a bone break easily is often the first sign of osteoporosis. But it doesn't need to be. Bone density is a term that describes how solid your bones are. Ordinary x-rays do not show bone loss until a large amount of bone mass is gone. The best way to measure bone density is by a DEXA-scan (dual-energy x-ray absorptiometry). Ask your doctor about this test if you think you are at risk for osteoporosis or if you are a woman around the age of menopause or older.

The DEXA-scan tells what your risk for a fracture is. It could show that you have normal bone density. Or, it could show that you have osteopenia or even osteoporosis.