Mansoura Nephrology and Dialysis Unit, Mansoura Faculty of Medicine, Internal Medicine Depament, Mansoura University, El Gomhoria St., Mansoura, 35516, Egypt.
Diagnostic and Interventional Radiology Department, Mansoura Faculty of Medicine, Mansoura, Egypt.
Int Urol Nephrol. 2023 Dec;55(12):3159-3165. doi: 10.1007/s11255-023-03589-y. Epub 2023 Apr 12.
Endothelial dysfunction is the primary step for the development of CKD-related cardiovascular disease. Early prediction and management can influence patient survival. Serum testing of FGF 23 hormone and urinary phosphate excretion were studied as predictors of all-cause cardiovascular morbidity in CKD patients; however, their relation to endothelial dysfunction is controversial. A combination of both in one index is hypothesized to increase their sensitivity in detecting endothelial dysfunction, especially in the early stages of CKD before the dominance of hyperphosphatemia, the original risk.
A cross-sectional comparative analysis between thirty CKD stage 3 patients and sixty stage 4-5 CKD patients was conducted. All patients were tested for markers of mineral bone disorders including serum FGF 23 and 24-h urinary phosphate excretion. A combination of both in one index (nephron index) is calculated and hypothesized to correlate with nephron number. Endothelial dysfunction was assessed by measuring the post-occlusion brachial flow-mediated dilatation (FMD).
In univariate and multivariate regression analyses, the nephron index was the only predictor of endothelial dysfunction in individuals with stage 3 CKD (r = 0.74, P 0.01). This was not applied to stage 4-5 CKD patients where serum phosphorus (r = - 0.53, P 0.001), intact PTH (r = - 0.53, P 0.001), uric acid (r = - 0.5, P 0.001), and measured GFR (r = 0.59, P 0.001) were the highest correlates to FMD; the Nephron index had the weakest correlation (r = 0.28, P = 0.02) and is not predictive of endothelial dysfunction.
Nephron index calculation showed better correlation with endothelial dysfunction than using any of its determinants alone in early stages of CKD when FGF 23 levels are just beginning to rise. In advanced CKD patients, hyperphosphatemia, hyperparathyroidism, hyperuricemia, and measured GFR are more reliable than nephron index.
内皮功能障碍是 CKD 相关心血管疾病发展的首要步骤。早期预测和管理可以影响患者的生存。研究了 FGF 23 激素的血清检测和尿磷排泄作为 CKD 患者全因心血管发病率的预测指标；然而，它们与内皮功能障碍的关系存在争议。假设将两者结合在一个指标中可以提高其检测内皮功能障碍的敏感性，尤其是在 CKD 的早期阶段，此时高磷血症尚未成为主要风险因素。
对 30 名 CKD 3 期患者和 60 名 CKD 4-5 期患者进行了横断面比较分析。所有患者均检测了矿物质骨代谢紊乱标志物，包括血清 FGF 23 和 24 小时尿磷排泄。假设将两者结合在一个指标（肾单位指数）中与肾单位数量相关。通过测量闭塞后肱动脉血流介导的扩张（FMD）来评估内皮功能障碍。
在单变量和多变量回归分析中，肾单位指数是 CKD 3 期个体内皮功能障碍的唯一预测指标（r=0.74，P<0.01）。这不适用于 CKD 4-5 期患者，其中血清磷（r=-0.53，P<0.001）、完整甲状旁腺激素（r=-0.53，P<0.001）、尿酸（r=-0.5，P<0.001）和测量的肾小球滤过率（r=0.59，P<0.001）与 FMD 相关性最强；肾单位指数相关性最弱（r=0.28，P=0.02），不能预测内皮功能障碍。
在 CKD 的早期阶段，当 FGF 23 水平刚刚开始升高时，与单独使用其任何决定因素相比，肾单位指数计算与内皮功能障碍的相关性更好。在晚期 CKD 患者中，高磷血症、甲状旁腺功能亢进、高尿酸血症和测量的肾小球滤过率比肾单位指数更可靠。
