Evaluation of cortical bone by peripheral quantitative computed tomography in peritoneal dialysis

Abstract

We evaluated cortical bone parameters by pQCT in 22 patients on continuous ambulatory peritoneal dialysis (CAPD) and compared them with those of 27 healthy controls. Cortical bone parameters (CBP) were obtained at the distal radius using a Stratec XCT 960 pQCT machine. In the PD patients we also determined BMD at the lumbar spine(LS) and femoral neck (FN) and total bone mineral content by areal densitometry; correlations were made with CBP. CAPD patients showed a significant increase in Total area (TA) (P = 0.006), in endosteal circumference (P < 0.0001) and in the buckling ratio (P < 0.0001) with a significant reduction in volumetric cortical BMD (VcDMD) (P = 0.04) and cortical thickness (cThK) (P < 0.0001). Total time in dialysis correlated negatively with Total BMD (P < 0.01) and VcBMD (P < 0.01). Age correlated positively with TA (P < 0.01), endosteal (P < 0.01) and periosteal circumferences (P < 0.01) and negatively with VcBMD (P < 0.01). Serum intact PTH levels correlated positively with endosteal (P = 0.04) and with periosteal perimeter (P = 0.01). No correlations were found between cortical area, VcBMD and cThK with serum intact PTH levels. TBMC correlated significantly with radial cortical content (P < 0.001) cA (P < 0.001) and cThK (P < 0.01) but not with total radial BMD, vcBMD or buckling ratio. No correlations were found between radial cortical content, density, area, thickness or buckling ratio and BMD measured at LS or FN. Conclusions: PD patients show cortical osteopenia with marked cortical thinning which may be partially mediated by PTH action. Good correlations were found between TBMC and some but not all radial cortical parameters. CBP were not correlated with areal BMD measured at the axial skeleton.