Association of hypogonadism and estradiol levels with bone mineral density in elderly men from the Framingham study

Background: Both hypogonadism and low estrogen levels adversely affect bone health in young men. In elderly men, who are at greatest risk for osteoporotic fracture, the influence of hypogonadism on bone mineral density remains unclear, as does the relative effect of estrogen status compared to hypogonadism. Objective: To examine the relation of hypogonadism and estrogen status to bone mineral density in elderly men. Design: Community-based, prospective cohort study. Setting: Framingham, Massachusetts. Patients: Male participants of the Framingham Study. Measurements: Total testosterone, total estradiol, and luteinizing hormone were measured in participants at all four biennial examinations from 1981 to 1989. Values from at least three of four examinations were averaged. Hypogonadism was defined as a mean testosterone level less than 10.4 nmol/L ( 0.2), even when alternate definitions of hypogonadism were used. In contrast, compared with the lowest estradiol quartile, men with higher estradiol levels had greater mean bone mineral density at all sites (for example, bone mineral density at the femoral neck was 0.84 g/cm 2 , 0.88 g/cm 2 , 0.86 g/cm 2 , and 0.91 g/cm 2 from the lowest to the highest estradiol quartile; P for trend = 0.002). The difference in mean bone mineral density between men in the lowest and those in the highest estradiol quartile levels was similar to the effect of 10 years of aging on bone mineral density. Conclusions: In elderly men, hypogonadism related to aging has little influence on bone mineral density, but serum estradiol levels have a strong and positive association with bone mineral density.