Department of Nephrology, Tokyo Kyosai Hospital, Nakameguro 2-3-8, Meguroku, Tokyo, 153-8934, Japan.
BMC Nephrol. 2012 Sep 26;13:122. doi: 10.1186/1471-2369-13-122.
Elderly patients with chronic kidney disease (CKD) are usually at a high risk of fractures due to both osteoporosis and CKD-mineral bone disease (MBD). A new marker is needed to prevent fractures and control CKD-MBD from the early to advanced stages of CKD. In the early stage of CKD, fibroblast growth factor 23 (FGF23) level increases before parathyroid hormone (PTH) and phosphate levels increase, and steadily increases with the progression of kidney disease. It has been reported that FGF23 is related to the overall fracture risk. We investigated the usefulness of FGF23 as a marker for evaluating the risk of vertebral fracture and CKD-MBD in elderly CKD patients.
One hundred and five elderly predialysis CKD patients who had never been treated for osteoporosis and had never used calcium supplements, vitamin D supplements, or phosphate binders were enrolled in this cross-sectional study in Tokyo, Japan. We investigated the prevalence of vertebral fracture and measured serum calcium, phosphate, 1,25(OH)2 vitamin D [1,25(OH)2D], intact PTH, FGF23, alkaline phosphatase, and urinary N-terminal telopeptide levels. Then, we examined the relationship between the level of FGF23 and those of bone-metabolism-related markers and identified markers associated with vertebral fractures in elderly CKD patients.
The background features of the patients were as follows: female, 32.4%; diabetes mellitus, 39.0%; average age (standard deviation), 73.2 (7.7) years; and estimated glomerular filtration rate (eGFR), 45.7 (24.1) ml/min/1.73 m2. Adjusted multivariate regression analysis showed that the natural logarithm value of FGF23 level [ln(FGF23)] was positively associated with body mass index (p = 0.002), serum phosphate level (p = 0.0001), and negatively with eGFR (p = 0.0006). Multivariate logistic regression analysis showed that vertebral fracture was independently associated with ln(FGF23) (adjusted odds ratio, 4.44; 95% confidence interval, 1.13-17.46). A receiver-operating-characteristic curve of ln(FGF23) showed that the optimal cutoff level of FGF23 indicative of vertebral fracture was 56.8 pg/ml (sensitivity, 0.82; specificity, 0.63).
FGF23 level was independently associated with the levels of bone-metabolism-related markers and vertebral fracture. FGF23 is a new candidate marker for detecting abnormalities of bone metabolism and vertebral fracture in elderly CKD patients.
患有慢性肾脏病（CKD）的老年患者由于骨质疏松症和 CKD 矿物质骨病（MBD）通常处于骨折高风险中。需要一种新的标志物来预防骨折，并在 CKD 的早期到晚期控制 CKD-MBD。在 CKD 的早期，成纤维细胞生长因子 23（FGF23）水平在甲状旁腺激素（PTH）和磷酸盐水平升高之前升高，并随着肾脏疾病的进展而稳定升高。据报道，FGF23 与总体骨折风险有关。我们研究了 FGF23 作为评估老年 CKD 患者椎体骨折和 CKD-MBD 风险的标志物的有用性。
在日本东京，我们进行了这项横断面研究，共纳入了 105 名从未接受过骨质疏松症治疗且从未使用过钙补充剂、维生素 D 补充剂或磷酸盐结合剂的老年透析前 CKD 患者。我们调查了椎体骨折的患病率，并测量了血清钙、磷酸盐、1,25（OH）2 维生素 D [1,25（OH）2D]、完整 PTH、FGF23、碱性磷酸酶和尿 N 末端肽水平。然后，我们检查了 FGF23 水平与骨代谢相关标志物之间的关系，并确定了与老年 CKD 患者椎体骨折相关的标志物。
患者的背景特征如下：女性，32.4%；糖尿病，39.0%；平均年龄（标准差），73.2（7.7）岁；估算肾小球滤过率（eGFR），45.7（24.1）ml/min/1.73m2。调整后的多变量回归分析显示，FGF23 水平的自然对数（ln[FGF23]）与体重指数呈正相关（p=0.002），与血清磷酸盐水平呈正相关（p=0.0001），与 eGFR 呈负相关（p=0.0006）。多变量逻辑回归分析显示，椎体骨折与 ln（FGF23）独立相关（调整后的优势比，4.44；95%置信区间，1.13-17.46）。ln（FGF23）的受试者工作特征曲线显示，指示椎体骨折的最佳 FGF23 截断值为 56.8pg/ml（敏感性，0.82；特异性，0.63）。
FGF23 水平与骨代谢相关标志物和椎体骨折独立相关。FGF23 是一种检测老年 CKD 患者骨代谢异常和椎体骨折的新候选标志物。
