Lumbar and femoral bone density in perimenopausal women with irregular cycles

The aim of the study was to evaluate the impact of irregular cycles on bone mass in perimenopausal women.

University clinic.

118 healthy women aged between 45 and 55 years were divided into three groups according to the previous year's menstrual history (premenopause: regular cycles; perimenopause: irregular cycles; early postmenopause: 1-3 years since the last menstrual cycle). Among the perimenopausal group, only women presenting intervals without menstruation longer than 3 months during the year of the study were selected. Bone mineral density of the lumbar spine and of the proximal femur was measured by dual energy X-ray absorptiometry (DEXA) at the start of the study and after 12 months.

The serum estradiol level was significantly lower in postmenopausal women and the FSH serum level showed a significant increase in perimenopausal and postmenopausal women in comparison with premenopausal controls. Bone density at L2-L4, femoral neck, greater trochanter, and total femur did not show significant differences at the beginning of the between-group study. Only the density in Ward's triangle was significantly lower in perimenopausal and postmenopausal women. After twelve months the densities of L2-L4, greater trochanter, Ward's triangle, and total femur showed a significant decrease in postmenopausal women in comparison. The perimenopausal group showed a significant decrease in total femur and Ward's triangle density in comparison with premenopausal.

The occurrence of marked irregularity of menstrual cycles preceding menopause can influence bone mass, in particular at the femoral site.