Volumetric Bone Density and Geometry Assessed by Peripheral Quantitative Computed Tomography in Uremic Patients on Maintenance Hemodialysis

The aim of this study was to establish, by means of peripheral quantitative computed tomography (pQCT) at the distal radius, the existence of cortical and/or trabecular osteopenia, and to assess the integrity of bone geometry in uremic patients undergoing maintenance hemodialysis. Our results show a clearcut selective reduction in volumetric cortical density, more evident in women (p = -0.0001) than men (p = 0.030), which appears to be independent of age and menopausal status. Trabecular density was not significantly changed in either sex. Cortical density of the patients correlated inversely with age (p = 0.003), duration of dialysis (p = 0.002) and parathyroid hormone (PTH) levels (p = 0.03). Trabecular density correlated only with age. Normally, cortical density is age-dependent and its reduction is accompanied by compensatory geometry changes. Compared with control subjects, in our female patients both cortical area and cortical thickness were reduced (p = 0.02 and 0.008), while cross-sectional area did not change (p = 0.67). Conversely, in the males only cross-sectional area was reduced (p = 0.02). In conclusion, in uremic patients we observed a selective cortical osteopenia, more evident in the female sex, and a sex-specific pattern of geometry impairment, with resultant apparent increased bone fragility in the uremic women. We suggest that the prolonged PTH excess could be responsible, directly and/or interacting with estrogen deficiency.