G333(P) Serum biomarkers, but not dual-energy x-ray absorptiometry (DXA), predict bone mineral density in children with chronic kidney disease

Introduction Currently available biomarkers and Dual-energy X-ray Absorptiometry (DXA) are thought to be poor predictors of bone mineral density (BMD). The 2017 KDIGO guidelines on CKD-MBD propose using DXA if it will affect patient management. We set out to determine the clinical utility of DXA and routine clinical biomarkers by comparing them with tibial cortical BMD measured by peripheral Quantitative Computed Tomography (pQCT), which clearly defines cortical and trabecular compartments and predicts future fracture risk. Methods We performed a prospective multi-centre cross-sectional study in 97 children (5–19 years) with CKD stages 4–5 and on dialysis. Children underwent hip and lumbar spine DXA and tibial pQCT. All DXA and pQCT data were expressed as age corrected Z-scores, and lumbar spine DXA was additionally corrected for height (BMAD Z-score). Imaging findings were correlated with routine serum biomarkers. Results Hip Z-score and lumbar spine BMAD Z-scores correlated significantly with each other (p PTH showed a positive correlation with tibial trabecular BMD (p=0.024) and a negative correlation with cortical BMD (p On multivariable linear regression analysis the significant and independent predictors of tibial cortical BMD were PTH (β-0.355, p Conclusions Routinely used biomarkers- calcium, alkaline phosphatase and PTH- when used together are weak to moderate predictors of BMD. No associations were seen with hip or lumbar spine DXA. DXA is not a clinically useful tool and should not be performed routinely.