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Study Finds Low Bone Density Undiagnosed in Many Post-Menopausal Women

A newly published study finds that almost half of post-menopausal women in the United States have low bone mineral density, a risk factor for osteoporosis. The study examined over 200,000 women 50 years of age and older and found that 7% had previously undiagnosed osteoporosis while an additional 40% had undiagnosed osteopenia, a condition that places women at high risk for osteoporosis. The study confirms that osteoporosis is one of the most under-diagnosed diseases in medicine and underscores the need for physicians to perform quick, painless bone mineral density tests on post-menopausal women.

Osteoporosis is a degenerative bone disease that is a threat to 28 millions Americans, mostly women. Literally meaning "porous bone," osteoporosis is characterized by a decrease in normal bone density due to the loss of calcium and collagen. A loss of bone density causes bones to become brittle, and in turn, leads to frequent fractures and other serious effects. It is estimated that one in two women over 50 will have an osteoporosis-related fracture.

A study called the National Osteoporosis Risk Assessment led by Ethel S. Siris, MD of the Columbia Presbyterian Medical Center in New York and her colleagues, attempted to determine how prevalent low bone density is among post-menopausal women. The study consisted of 200,160 post-menopausal women 50 years of age or older who saw physicians at primary care practices in 34 U.S. states between September 1997 and March 1999. None of the women had been diagnosed with osteoporosis prior to the study.

All of the women in the study were given portable bone density scans to determine their bone mineral density at their heels, fingers, and forearms. The women did not undergo dual x-ray absorptiometry (DEXA), one of the most common methods of diagnosing osteoporosis, because the researchers wanted to determine the usefulness of inexpensive, portable bone density tests that can be conveniently performed during routine office visits.

Dr. Siris and her colleagues found that 7.2% of the women unknowingly had osteoporosis based on the results of the bone density tests. After a year of follow-up, the researchers found that these women were 350 times more likely to experience a bone fracture than women with average bone mineral density. Dr. Siris’ study also found that nearly 40% of the women previously under-diagnosed osteopenia, a condition of low bone mineral density that makes them 80% more likely to experience a bone fracture than women with average bone mineral density.

The researchers did find that certain factors influenced the women’s likelihood of having low bone mineral density. These factors included:

  • Smoking or a history of smoking (these women were 14% to 16% more likely to have low bone density than non-smokers)
  • Asian-American or Hispanic descent (Caucasian women were also more likely to have osteoporosis compared with African-American women)
  • Family history of osteoporosis

On the other hand, women who used hormone replacement therapy or those who were overweight or drank alcohol were less likely to have osteoporosis.

The researchers acknowledge there may be some conflict of interest with the study. Merck, the maker of the osteoporosis drug Fosamax (generic name, alendronate) provided funding for the study, as did the International Society for Clinical Densitometry, an organization that receives funding from the medical imaging industry. However, both the researchers and the Journal of the American Medical Association that published the study are confident that the study results are not biased and that women benefit from knowing that osteoporosis and low bone mineral density are often under-diagnosed.

Women with osteoporosis or low bone mineral density can help treat their condition and reduce their risk of bone fractures by taking medication, consuming adequate amounts of calcium and vitamin D, and exercising. Click here to learn about the Bone-Building Checklist: 5 Ways to Prevent Osteoporosis.  

Experts recommend that the following women receive bone mineral density tests:

  • Post-menopausal women with at least one additional risk factor for osteoporosis (other than menopause)
  • All women older than 65 regardless of risk factors
  • Post-menopausal women with bone fractures
  • Women considering therapy for osteoporosis, if bone mineral density (BMD) testing would affect the decision
  • Women who have been on hormone replacement therapy (HRT) for prolonged periods of time

Additional Resources and References