Endocrine Abstracts

High-resolution peripheral computed tomography (HR-pQCT) (XtremeCT, Scanco) obtains three-dimensional images of the distal radius with a resolution of 82 microns, which enables detailed study of the microarchitecture of cortical and trabecular bone. Better description of the microarchitectural changes in bone with ageing will improve understanding of which preventative and therapeutic interventions are most likely to be effective.

The aim of this study was to identify differences in cortical and trabecular bone in men and women at peak bone mass and older age.

We studied 110 male and female healthy volunteers ages 30–32 and over 70. The study was approved by the local research ethics committee. We analysed HR-pQCT images with standard software and a cortical microarchitecture programme supplied by Scanco.

Radius cortical density was lower after age 70 than at ages 30–32 in men and women (888 vs 952, 914 vs 1006 mg/cm³, P<0.001) due to higher porosity, greater pore size and lower tissue mineral density. Age differences in trabecular architecture differed between men and women. In men, trabecular thickness, but not trabecular number was lower in the older age group. In women, trabecular number, but not trabecular thickness was lower in the older age group. Older women had greater trabecular separation and trabecular inhomogeneity (the S.D. of trabecular separation) than younger women (0.25 vs 0.17 mm, P<0.01), but trabecular separation and inhomogeneity did not differ between older and younger men (0.18 vs 0.15 mm).

In conclusion, patterns of cortical bone loss with ageing are similar in men and women, but patterns of trabecular bone loss differ, with greater disruption of trabecular microarchitecture in women. It is possible that cortical bone loss is due to factors such as PTH and IGF1, which change similarly with age in men and women, and that trabecular disruption results from decreasing oestrogen levels.