Osteoporosis: The Bone Thief

Helen grew up on a dairy farm in the Midwest. She drank 3 glasses of milk a day as a child. After high school she began work as a secretary in a local law office where she spent her entire career. Helen never jogged, walked as exercise, or played tennis. She went through menopause at age 47. Shortly before retirement at age 61, she slipped on a small rug in her kitchen and broke her hip. After Helen recovered, she needed a cane to walk.

Helen had osteoporosis, but she didn’t know it. Osteoporosis is a disease that thins and weakens bones to the point where they break easily—especially bones in the hip, spine (backbone), and wrist. You can lose bone over many years. Because you may not notice any symptoms until a bone breaks, osteoporosis is called the “silent disease.”

Bone is living tissue. Special cells called osteoclasts are constantly breaking down old bone as other cells known as osteoblasts are replacing it with new tissue. As people age, more bone is broken down than is replaced. The inside of bone normally looks like a honeycomb. In osteoporosis the spaces in this honeycomb grow larger because much more bone is destroyed than is replaced. This makes your bones weaker.

Experts do not fully understand why this happens. They do know that after women go through menopause, levels of the female hormone estrogen are much lower. These lower hormone levels can lead to bone loss and osteoporosis. Other causes of this disease include too little exercise and a diet too low in calcium and vitamin D.

Who Gets Osteoporosis?

More than 10 million Americans have osteoporosis. Eighteen million more have lost enough bone to make them more likely to develop this disease. More than 80% of these 28 million are women. One out of 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. Women who have a family history of the disease, an early menopause, or small body frames are at greatest risk.

Osteoporosis is not just an “old person’s disease.” It can happen at any age, but the risk grows as you get older. After age 30, bone loss begins to occur very slowly. In women the rate of loss increases for several years after menopause, then slows again, but continues. As men age, they do not have the same kinds of striking hormone losses as women do in mid-life. In men the drop 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. 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 density is gone. The most exact way to measure bone density is by a DEXA-scan (dual-energy x-ray absorptiometry). This is done on the whole body. 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 can show whether you are at risk for a fracture. If you have already broken a bone and your doctor thinks you might have osteoporosis, the test can confirm the diagnosis. If more than one test is done at least a year apart, your doctor can compare the test results over time. Then he or she can see if the treatment has succeeded in slowing your bone loss.

The test results are reported as a number. If your doctor says your result was –2.5 SD (standard deviation) or more, this means you have osteoporosis. A test finding of –1SD to –2.5SD means you have some bone loss. This is known as osteopenia, and you are at risk of developing osteoporosis.