Malluche Hartmut H, Davenport Daniel L, Cantor Tom, Monier-Faugere Marie-Claude
Division of Nephrology, Bone and Mineral Metabolism, Department of Internal Medicine and
Department of Surgery, University of Kentucky, Lexington, Kentucky; and.
Clin J Am Soc Nephrol. 2014 Jul;9(7):1254-62. doi: 10.2215/CJN.09470913. Epub 2014 Jun 19.
Use of bone mineral density (BMD) by dual-energy x-ray absorptiometry (DXA) is controversial for diagnosing bone loss in CKD patients on dialysis. The alternative quantitative computed tomography (QCT) is expensive and requires high radiation exposure. This study compared the two techniques and evaluated serum biochemical parameters for prediction of bone loss.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This prospective study enrolled patients from dialysis centers throughout Kentucky. BMD of the spine and hip was measured at baseline and after 1 year by DXA and QCT. Customary and novel serum biochemical parameters were obtained at the same times, including calcium, phosphorus, whole and intact parathyroid hormone, bone-specific alkaline phosphatase, procollagen type 1 N-terminal propeptide, tartrate-resistant acid phosphatase-5b, Dickkopf-1, fibroblast growth factor, and sclerostin. Rates of detection of osteoporosis by DXA and QCT were compared. Correlations were calculated between baseline biochemical parameters and BMD at baseline and changes over 1 year. Multivariable regression was performed to adjust for age, sex, body mass index, and race.
Eighty-one patients completed the study (mean age=52.6 ± 12.3 years, 56% men, 53% African American, and median dialysis vintage=41 months). At baseline, QCT and DXA of the spine identified similar rates of osteoporosis (13.6% and 13.6%), but at the hip, DXA identified more osteoporosis (22.2% versus 13.6%). At any site and by either method, 33.3% of the patients were osteoporotic. Baseline BMD correlated with sclerostin, intact parathyroid hormone, bone-specific alkaline phosphatase, tartrate-resistant acid phosphatase-5b, and fibroblast growth factor. At 1 year, hip QCT identified a higher number of patients experiencing bone loss (51.3%) than DXA (38.5%). After multivariable adjustment, baseline sclerostin and tartrate-resistant acid phosphatase-5b predicted bone loss measured by QCT of the hip; procollagen type 1 N-terminal propeptide predicted cortical spine bone gain by QCT.
QCT identified prospectively more bone loss at the hip than DXA. The baseline serum biochemical parameters sclerostin and tartrate-resistant acid phosphatase-5b were noninvasive independent predictors of bone loss in CKD patients on dialysis.
双能X线吸收法（DXA）测定骨矿物质密度（BMD）在诊断接受透析的慢性肾脏病（CKD）患者骨质流失方面存在争议。另一种方法定量计算机断层扫描（QCT）成本高昂且辐射暴露量大。本研究比较了这两种技术，并评估了血清生化参数对骨质流失的预测作用。
设计、地点、参与者与测量方法：这项前瞻性研究纳入了肯塔基州各地透析中心的患者。在基线期及1年后，采用DXA和QCT测量脊柱和髋部的BMD。同时获取常规及新型血清生化参数，包括钙、磷、总甲状旁腺激素和完整甲状旁腺激素、骨特异性碱性磷酸酶、1型前胶原N端前肽、抗酒石酸酸性磷酸酶-5b、Dickkopf-1、成纤维细胞生长因子和硬化蛋白。比较DXA和QCT检测骨质疏松症的发生率。计算基线生化参数与基线期BMD以及1年期间变化的相关性。进行多变量回归以校正年龄、性别、体重指数和种族。
81例患者完成了研究（平均年龄=52.6±12.3岁，56%为男性，53%为非裔美国人，透析中位时间=41个月）。在基线期，脊柱的QCT和DXA检测到的骨质疏松症发生率相似（分别为13.6%和13.6%），但在髋部，DXA检测到更多骨质疏松症患者（22.2%对13.6%）。无论采用哪种方法，在任何部位，33.3%的患者患有骨质疏松症。基线BMD与硬化蛋白、完整甲状旁腺激素、骨特异性碱性磷酸酶、抗酒石酸酸性磷酸酶-5b和成纤维细胞生长因子相关。1年后，髋部QCT检测到骨质流失的患者数量（51.3%）高于DXA（38.5%）。经过多变量校正后，基线硬化蛋白和抗酒石酸酸性磷酸酶-5b可预测髋部QCT测量的骨质流失；1型前胶原N端前肽可预测QCT测量的皮质脊柱骨量增加。
前瞻性研究显示，QCT检测到的髋部骨质流失比DXA更多。基线血清生化参数硬化蛋白和抗酒石酸酸性磷酸酶-5b是接受透析的CKD患者骨质流失的非侵入性独立预测指标。
