Changes in bone mineral density with age, menopausal status and body mass index in Turkish women

Abstract

Objective The aim was to evaluate changes in bone mineral density (BMD) with age and body mass index (BMI) in healthy pre- and postmenopausal women living in the urban areas of Turkey.Design The study was prospective, carried out from 1993 to 1997.Setting The study was carried out at a university hospital, the Istanbul University Cerrahpasa School of Medicine, Turkey.Patients The study group consisted of 849 healthy women of ages 20–84 years, admitted to the Istanbul University Cerrahpasa School of Medicine. The cases were divided into age groups, starting with 20–29 years and ending with 70 years and over. For regression analysis, the cases were further regrouped as 20–39, 40–59 and 60 years and over. Dual energy X-ray absorptiometry (DEXA) was used to measure BMD in the lumbar vertebrae (L2–L4) and in the classical locations of the proximal femur such as the femoral neck, the Ward's triangle and the trochanter. Multiple regression analysis was performed for the evaluation of annual changes in BMD with respect to age and/or BMI.Results A significant decrease in BMD started especially in the 40–49 age group, matching the average age of menopause in the study population. In contrast to the non-significant changes in the 20–39 age group, a significant decrease in BMD in the 40–59 age group, which included the average age of menopause, was detected in all locations (p < 0.0001). In addition to the significant effect of the menopause on BMD, an association between BMD and BMI was found in every location and age group (p = 0.02 to p < 0.0001). The total bone loss in the 70 and over age group, in comparison with the 30–39 age group, was 18.78% in L2–L4, 21.69% in the femoral neck, 32.68% in the Ward's triangle and 14.11% in the trochanter. Corresponding values between age groups 70 and over and 60–69 were 0.25%, 7.62%, 11.94% and 8.29%, respectively. Women in the older age groups had a slower decline in BMD in the lumbar vertebrae, in comparison with the proximal femur. Moreover, the maximum postmenopausal total bone mineral loss was in the Ward's triangle.Conclusions The present results, confirming the results of other studies, have revealed a significant association between BMD and the menopausal startus of women in the Turkish population. Additionally, a significant correlation has been detected between BMI and BMD, regardless of location and age.