In the longest study of bone loss in postmenopausal women to date, on average, bone mineral density (BMD) at the femoral neck (the most common location for a hip fracture) had dropped by 10% in 25 years – less than expected based on shorter studies.
Specifically, average BMD loss at the femoral neck was 0.4% per year during 25 years in this new study from Finland, compared with a drop of 1.6% per year over 15 years reported in other cohorts.
Five-year BMD change appeared to predict long-term bone loss. However, certain women had faster bone loss, indicating that they should be followed more closely.
“Although the average bone loss was 10.1% ... there is a significant variation in the bone loss rate” among women in the study, senior author Joonas Sirola, MD, PhD, associate professor, University of Eastern Finland, and coauthor Heikki Kröger, MD, PhD, a professor at the same university, explained to this news organization in an email, so “women with fast bone loss should receive special attention.
The findings from the Kuopio Osteoporosis Risk Factor and Prevention study by Anna Moilanen and colleagues were published online October 19 in the Journal of Bone and Mineral Research.
Several factors might explain the lower than expected drop in femoral neck BMD (the site that is used to diagnose osteoporosis), Dr. Sirola and Dr. Kröger said. BMD depends on a person’s age, race, sex, and genes. And compared with other countries, people in Finland consume more dairy products, and more postmenopausal women there take hormone replacement therapy (HRT).
“If otherwise indicated, HRT seemed to effectively protect from bone loss,” the researchers noted.
Also, the number of women who smoked or used corticosteroids was low, so bone loss in other populations may be higher. Moreover, the women who completed the study may have been healthier to start with, so the results should be interpreted with caution, they urge.
Nevertheless, the study sheds light on long-term changes in BMD in postmenopausal women and “stresses the importance of high peak bone mass before menopause and keeping a healthy weight” during aging to protect bone health, they say.
Indeed the work “changes our understanding of bone loss in older women,” said Dr. Kröger in a press release from the university.
Check BMD every 5 years after menopause
Invited to comment, American Society of Bone and Mineral Research President Peter R. Ebeling, MD, who was not involved with the research, noted key findings are that the rate of femoral neck bone loss after perimenopause was far less than previously expected, and 5-year BMD change appeared to predict long-term bone loss in postmenopausal women.
“We know bone loss begins 1 year before menopause and accelerates over the next 5 years,” Dr. Ebeling, from Monash University, Melbourne, added in an email. “This study indicates some stabilization of bone loss thereafter with lesser effects of low estrogen levels on bone.”
“It probably means bone density does not need to be measured as frequently following the menopause transition and could be every 5 years, rather than every 2 years, if there was concern about continuing bone loss.”