Urine Test Can Indicate a Woman’s Risk of Bone Fracture, Pitt Study Finds
Women in their 40s and early 50s had a 59 percent greater risk of bone fracture as they aged when they had above-normal levels of N-telopeptide (NTX) – the byproduct of bones breaking down – in their urine, compared with women who had low NTX levels. When women with high NTX levels also had a low spinal bone density measurement, their risk of fracture increased nearly three-fold.
The study is the first to look for signs of bone breakdown in younger, premenopausal women in an effort to determine if such signs can predict the risk that these women will suffer fractures as they age.
The results were published today in the online edition of Menopause, the journal of The North American Menopause Society
. The report will be published in the journal’s November print issue.
“Bone fractures – particularly in the hip, wrist and back – have serious consequences, including disability and death,” said Jane Cauley, Dr.P.H.
, professor of epidemiology, GSPH, and lead author of the study. “Knowing a woman’s risk of fracture can help doctors determine the best course of action to protect her bones as she enters menopause, a time when estrogen deficiency negatively affects skeletal health.”
By the time a woman turns 50, her risk of a fracture at some point in the remainder of her life is estimated to be at least 40 percent. Fractures are more common for these women than heart attacks, strokes and breast cancer combined.
During menopause, bone remodeling increases, leading to an imbalance between bone formation and bone resorption, or the process by which bones are broken down and their minerals are returned to the blood. This remodeling persists for several years and is associated with an increased rate of bone loss, making it easier for bones to fracture.
Cauley and her colleagues used data from 2,305 premenopausal or perimenopausal women aged 42 to 52 collected over an average of 7.6 years as part of the Study of Women’s Health Across the Nation
(SWAN). Participants were from Boston, Detroit, Los Angeles, Pittsburgh and Oakland, Calif.
SWAN examines the physical, biological, psychological and social health of women during their middle years. The goal is to help scientists, health care providers and women learn how mid-life experiences affect health and quality of life during aging.
Collaborators on this study include Michelle E. Danielson, Ph.D., Yue-Fang Chang, Ph.D., Kristine Ruppert, Dr.P.H., Leslie Meyn, M.S., and Beth A. Prairie, M.D., M.S., all of the University of Pittsburgh
; Gail A. Greendale, M.D., and Carolyn J. Crandall, M.D., M.S., both of the University of California Los Angeles
; Joel S. Finkelstein, M.D., and Robert M. Neer, M.D., both of Massachusetts General Hospital
; Joan C. Lo, M.D., of Kaiser Permanente Northern California
; and MaryFran R. Sowers, Ph.D., of the University of Michigan
This research was supported by the National Institutes of Health
(NIH), Department of Health and Human Services, through the National Institute on Aging, the National Institute of Nursing Research and the NIH Office of Research on Women’s Health (grants NR004061, AG012495, AG012505, AG012531, AG012553 through AG012535, AG012539 and AG012546). This work also was supported by Department of Defense grant DAMD17-96-6118; NIH grants K24-DK02759 and RR-1066; the Iris Cantor-University of California, Los Angeles Women’s Health Center; and University of California, Los Angeles Center of Excellence in Women’s Health grant RFP 282-97-0025.