Many Postmenopausal Women Have Low Bone Density, But Don't Know It.

2001 DEC 27 - (NewsRx.com & NewsRx.net) -- Almost half of the postmenopausal women enrolled in a large national study had undetected low bone mineral density, including 7% with osteoporosis, and were at increased risk of fracture within a year, according to a new study.

Ethel S. Siris, MD, of Columbia University College of Physicians and Surgeons, New York, and colleagues report the initial findings from the National Osteoporosis Risk Assessment (NORA), the largest study of osteoporosis conducted to date in the United States. A total of 200,160 postmenopausal women age 50 and older with no previous diagnosis of osteoporosis were recruited from the practices of 4236 primary care physicians in 34 states and enrolled in the study between September 1997 and March 1999. Although most participants (89.7%) were white, more than 18,000 minority women were included.

Osteoporosis is thinning of the bones with a reduction in bone mass due to depletion of calcium and bone protein. People with osteoporosis are more likely to experience fractures that are often slow to heal. A condition known as osteopenia represents low bone mass, but not to the severe extent of osteoporosis. Both osteoporosis and osteopenia can be diagnosed by bone density scans. According to the authors, dual-energy x-ray absorptiometry (DXA) of the hip and spine is currently the "gold standard" for measurement of bone mineral density (BMD).

However, large segments of the population at risk for osteoporosis and fracture have not been evaluated, and the usefulness of peripheral bone mineral density measurements (such as at the forearm, finger or heel) for short-term prediction of fracture risk is uncertain, according to the study published in the December 12, 2001, issue of Journal of the American Medical Association.

Each woman enrolled in NORA completed a questionnaire and had a peripheral BMD measurement at no cost, and 163,979 participants provided information for a follow-up questionnaire 12 months after enrollment, including questions about new fractures.

"Using World Health Organization criteria, 39.6% had osteopenia and 7.2% had osteoporosis," the authors report.

"Age, personal or family history of fracture, Asian or Hispanic heritage, smoking, and cortisone use were associated with significantly increased likelihood of osteoporosis; higher body mass index, African-American heritage, estrogen or diuretic use, exercise, and alcohol consumption significantly decreased the likelihood," they write.