Abstract
Population studies in older men have reported a positive correlation between bioavailable oestradiol concentration and bone mineral density (BMD). A correlation between testosterone concentration and BMD has been demonstrated in some studies, the data being limited. Cauley et al. analysed data from a random sample of men enrolled in the Osteoporotic Fractures in Men Study (MrOS) to determine the longitudinal association between sex hormone concentrations and BMD.
The study randomly sampled 1602 men from the 5995 participants aged over 65 y enrolled in the MrOS. Participants reporting the use of osteoporosis medication, oral corticosteroids and hormone therapy were excluded. After exclusions, 1238 men were included in cross-sectional analyses and 969 in longitudinal analyses. Combined gas chromatography mass spectrometry and liquid chromatography mass spectrometry were used to measure testosterone and oestradiol concentrations in baseline fasting samples. BMD and area of the total hip were measured using dual energy X-ray absorptiometry. BMD was measured at baseline and then subsequently once or twice over a 4.6 y follow-up period.
Oestradiol concentrations correlated positively with BMD, with little association with testosterone concentration after adjustment for age and weight. Men with a bioavailable oestradiol concentration of <40 pmol/L experienced a 38% faster rate of BMD loss compared with those with an oestradiol concentration of >66 pmol/L. There was no association between bioavailable testosterone concentration and hip BMD loss. The rate of hip BMD loss increased in men with a sex hormone binding globulin (SHBG) concentration between 49 and 60 nmol/L.
With a primarily Caucasian cohort, an association between sex hormone concentration and BMD in different racial groups was not determined. As there were no repeated measures of sex hormones and SHBG, the authors were unable to correlate changes in sex hormone concentrations with changes in BMD.