Rate of Change in Bone Mineral Density Through Menopause

Abstract

In the United States, there are roughly 1.5 million osteoporosis related fractures each year. With increasing age, the risk of osteoporosis increases. Nearly 33.6 million Americans over the age of 50 have osteopenia, a precursor to osteoporosis. The average onset of menopause is 51 years. There is a decreasing bone mineral density (BMD) with the onset of menopause; however, what is less known is the rate of change in BMD in women through menopause. PURPOSE: It is the purpose of this study to track the rate of change in BMD as a woman goes through menopause. METHODS: Fifty-seven women were scanned three consecutive years using a Dual Energy X-ray Absorptiometry (DEXA). The women were classified as either perimenopausal or menopausal according to their self-reported symptoms and frequency of menstruation. Perimenopause was denned as the period before the onset of menopause with symptoms (i.e. change in flow and hot flashes) without a cessation of menses. Menopause was categorized as cessation of menses for at least 12 consecutive months. The participants were divided into three groups depending on their menstrual status for the three year period. Group 1 (N=17) was perimenopausal for all threeyears and Group 2 (N=27) menopausal for the three years. Group 3 (N=1 3) was perimenopausal in years one and two, but became menopausal in year three. A 3 × 3 repeated measures ANOVA was performed to test for differences between the groups over time. RESULTS: No significant differences were observed between the groups with regard to BMD (F2,54=2.397, p = .101). Mean values for each group are 1.27, .43, and .53 for BMD t-score for Group 1, 2, and 3, respectively. Within subjects analysis revealed a significant interaction for BMD between time and menstrual status (F4,108=5.368, p = .001). CONCLUSIONS: The results suggest that there is a decline of BMD over time; however, the change is not different between those that are perimenopausal or menopausal or those that move from perimenopause to menopause. The results indicate that there is possibly a dramatic decline in BMD during the postmenopausal years.