Body weight and/or endogenous estradiol as determinants of cortical bone mass and bone loss in healthy early postmenopausal women.

The objective was to study the independent relationships of body mass index and endogenous estradiol to cortical bone mineral density and the rate of cortical bone loss at the radius in healthy early postmenopausal women. Fifty-one healthy early postmenopausal women (aged 58-66 years) participated. The women were a subset of a population participating in a 10-year longitudinal study to elucidate the influence of dietary calcium on the rate of cortical bone loss. Cortical bone mineral density at the radius, body weight and body height were measured annually (1979-89). Concentrations of sex steroids were measured in serum samples collected during the last year of follow-up (1989). Endogenous estradiol levels, although significantly positively correlated with body mass index, were not independently related to bone mass indices of the radius. Body mass index, on the other hand, was found to be positively related to cortical bone mineral density and negatively to the rate of bone loss, even after adjustments had been made for confounding factors. Our results suggest that the level of total estradiol is not an important determinant of cortical bone mass indices in healthy early postmenopausal women. Other factors of overweight such as mechanical loading may be important.