Causes of Bone Loss

In addition to aging, other factors influence the strength and density of your bones:

• Hormonal changes, especially a drop in estrogen levels, increase bone loss. When women go through menopause, their estrogen levels drop to one-third of what these levels were during the childbearing years. Even this much estrogen helps bones to hold onto some of their strength. But since there is more bone loss than bone rebuilding after menopause, most women lose at least some bone after their periods stop.
• If you go into early menopause due to chemotherapy (or from natural causes, or surgery that removed the ovaries), your body's estrogen levels can drop quickly and significantly. And if you are a post-menopausal woman who had been taking hormone replacement therapy but had to stop when you were diagnosed with breast cancer, the sudden withdrawal of replacement hormones will cause your body's estrogen levels to drop abruptly.
• A family history of weak bones increases your risk of osteoporosis.
• Being thin is associated with more bone loss. Body fat increases certain types of estrogen, so thin women tend to have lower levels of estrogen. As a result, age- and estrogen-related declines in bone mass will have a greater effect on them.
• Some diets can cause bone loss. "Yo-yo" dieting—losing a lot of weight, putting it back on, and losing it again—can lead to poor nutrition and shifts in hormone levels. These ups and downs can cause significant bone loss.
• Certain diseases may lead to hormonal imbalance that causes bone loss. These diseases include hyperthyroidism, diabetes mellitus, Cushing's disease, anorexia nervosa, and chronic kidney failure.
• Some medications cause bone loss, including corticosteroids, thyroid drugs, and anti-seizure drugs; some diuretics; and chronic use of barbiturates. Some hormonal therapies for breast cancer are also associated with bone loss. Ask your doctor for specifics about any medications you may be taking.
• Regular smoking leads to significant bone loss (smoking results in an earlier menopause, poor nutrition, chronic ill health and less activity).
• Heavy alcohol use also leads to bone loss (women should probably have no more than 2 alcoholic drinks per day, and binge drinking may be especially harmful). The combination of smoking and alcohol use is particularly unhealthy and stressful for bone tissue.
• Not getting enough calcium, vitamin D, or magnesium can lead to bone loss. Women over 70 may have a harder time getting these nutrients in their diet or absorbing them properly.
• Prolonged bed rest or inactivity also contributes to bone loss. If you were an astronaut, you'd have this same problem. Without gravity, your bones aren't working very hard and they lose strength more easily.
• Racial and ethnic characteristics influence the risk of osteoporosis. Caucasian and Asian women lose bone density and mass faster than do African, African-American, American Indian, East Indian, and Latina women.

This section was made possible by an unrestricted educational grant from AstraZeneca.