FP405EVALUATION OF BONE MICROARCHITECTURE BY HIGH-RESOLUTION PERIPHERAL QUANTITATIVE COMPUTED TOMOGRAPHY IN PATIENTS WITH CHRONIC KIDNEY DISEASE: COMPARISON WITH TRANSILIAC BONE BIOPSY

Abstract

Introduction and Aims: High-resolution peripheral quantitative computed tomography (HR-pQCT) is a noninvasive imaging technique that assesses trabecular and cortical bone microarchitecture in vivo. The purpose of our study is to evaluate, for the first time, the correlation between HR-pQCT measures and transiliac bone biopsy (Bx) in chronic kidney disease (CKD) patients. Methods: We measured bone mineral desnsity (BMD) by HR-pQCT and dual energy x-ray absorptiometry (DXA) in 31 CKD stage 5D patients. Biopsies were analyzed by 2D quantitative histomorphometry, where both total and mineralized trabecular bone volume (2D BV/TV and 2D Md.V/TV, respectively) were measured. Results: Patients (19 males) were 41 ± 11 years old, with a dialysis vintage of 28 months, BMI of 24 kg/m2, serum Ca of 8.4 ± 0.6 mg/dl; P of 3.4±1.5 mg/dl; alkaline phosphatase 93 (71 -145) U/L; PTH 463 ± 343 pg/ml; 25-vitamin D 25 (18 - 32) ng/ml and sclerostin 1.03 (0.51 - 1.83) ng/ml. 2D BV/TV correlated significantly with height; lumbar spine (r = 0.70) and total femur (r = 0.59) DXA; and modestly with HR-pQCT BV/TV at the radius (r = 0.42; p< 0.05) but not at the tibia. 2D Md.V/TV correlated significantly with age; height; lumbar spine (r = 0.67) and total femur (r = 0.63) DXA; and HR-pQCT BV/TV (r = 0.50; p<0.05) only at the radius. Conversely, a strong correlation was found between 2D cortical porosity (Ct.Po) and HR-pQCT cortical bone density (Dcomp) both at radius and tibia (r = -0.60 and -0.64, respectively; p <0.05). We found significant negative correlations between cortical density measured by HR-pQCT, and age, time on dialysis, PTH and alkaline phosphatase in the distal radius and tibia. The trabecular density and BV/TV, as measured by HR-pQCT, correlated with the age at the distal tibia and radius, and sex hormones, only at the radio. Conclusions: There was a good correlation between HR-pQCT and transiliac bone biopsy with respect to cortical compartment. On the other hand, in trabecular bone, despite being statistically significant and greater than that described for the general population, the correlations between both methods were modest, indicating that HR-pQCT cannot be used to predict 2D BV/TV. Further, larger studies are needed as well as studies to determine if these noninvasive measures can predict fracture.