Bone Abstracts

Background: Risk of fracture in chronic kidney disease (CKD) population is high and it is associated with increased mortality. CKD affects bone quality through changes in bone turnover, microarchitecture, and mineralization. Secondary hyperparathyroidism has different effects on cortical and trabecular bone but dual-energy X-ray absorptiometry (DXA) is unable to effectively differentiate these bone compartments. High resolution peripheral quantitative computed tomography (HRpQCT) can overcome this limitation.

Aim: To compare bone mineral density (BMD) and micro-architectural parameters in CKD stages 4–5D (i.e. including dialysis) patients with controls.

Methodology: This is a cross-sectional study of CKD stages 4–5D patients and their age- and sex-matched controls with estimated glomerular filtration rate (eGFR) >60 ml/min per1.73 m². We used DXA to measure areal BMD (aBMD) of LS, hip and forearm. XtremeCT was used to obtain HRpQCT images of distal radius and tibia. This study has the Local Research Ethics Committee approval (ref 13/YH/0078).

Results: This is preliminary results from 20 CKD patients (13 pre-dialysis, and seven dialysis) in our study and their controls. This is an ongoing cross sectional study examining imaging and bone turnover markers utility to predict bone histomorphometry. Mean eGFR was 12 ml/min per 1.73 m² for pre-dialysis patients and 78 ml/min per 1.73 m² for controls. 25% of each group were female. We found that CKD patients had lower BMD measured by both techniques compared to controls. CKD patients had lower aBMD by DXA but this was only significant at the hip.

At the tibia, total vBMD was significantly lower in CKD compared to controls and there was a trend towards lower cortical and trabecular vBMD but this was not significant. At the radius, total vBMD was lower in CKD but trabecular vBMD was significantly lower compared to controls. Meanwhile, cortical vBMD in CKD at this site was similar to controls. We also found thinner cortical bone at the tibia and thinner trabeculae at the radius in CKD.

Conclusion: Preliminary data suggests that CKD is associated with different effects in trabecular and cortical bone. HRpQCT is a useful research tool in detecting bone changes in CKD although this needs to be verified in larger study and with bone histomorphometry.