Longitudinal evaluation of preimenopausal femoral bone loss: Effects of a low-dose oral contraceptive preparation on bone mineral density and metabolism

To characterize the pattern of biochemical markers of bone metabolism and f emoral bone mineral density in eumenorrheic and oligomenorrheic perimenopau sal women, and assess the effects of a low-dose oral contraceptive (OC) on bone metabolism and femoral bone density, bone biochemical markers and femo ral bone density (measured at the neck, Ward's triangle and trochanter regi ons) were evaluated in a longitudinal 2-year follow-up study. The study was conducted in healthy, normally menstruating perimenopausal women (n = 18), perimenopausal oligomenorrheic women (n = 18), and perimenopausal oligomen orrheic women treated with an OC containing 20 mu g ethinylestradiol plus 0 .15 mg desogestrel (n = 19). The results were analyzed by factorial of repe ated measures analysis of variance, as appropriate. During the observation period, in normally menstruating women there were no changes in the menstru al cycle, plasma FSH and estradiol levels, biochemical markers of bone turn over or femoral bone density. In oligomenorrheic untreated women an increas e in cycle length with a concomitant decrease in plasma estradiol and an in crease in plasma FSH levels were found (p < 0.05). In this group a signific ant increase in urinary excretion of hydroxyproline and in plasma osteocalc in levels with a concomitant significant decrease in femoral bone density ( p < 0.05) occurred. In OC-treated women, osteocalcin plasma levels and urin ary excretion of hydroxyproline significantly (p < 0.05) decreased, leading to a significant (p < 0.05) increase in femoral bone density. It is conclu ded that perimenopausal OC administration can avoid the increase in bone tu rnover and the decrease in femoral bone density due to the perimenopausal i mpairment of ovarian function.