Objective To evaluate the clinical significance of serum cystatin C ( Cys C) in early renal impairment in patients with hypertension, and provide the reference for Cys C in the clinical application. Methods 318 patients with primary hypertension and suspected early renal impairment were enrolled. Serum Cys C and the clearance of 99mTcdiethy lenetriaminepentaacetic acid (99mTc-DTPA) were determined. 318 patients were classified into 2 groups according to the clearance of 99m Tc-DTPA (renal impairment group: 127 cases and control group: 191 cases). The receiver operating characteristic (ROC) curve was used to confirm the cut-off value, and the sensitivity, specificity and Youden index were calculated. The accuracy of diagnosing the early renal impairment by serum Cys C was evaluated. The repeatability was assessed simultaneously, and the reliability was analyzed. Results According to the ROC curve, the best cut-off value of diagnosing patients with primary hypertension and early renal impairment was 1.26 mg/L. The sensitivity and specificity were 84. 3％ and 79. 1％. The positive and negative predictive values were 72.8％ and 88.3％ respectively. The positive and negative likelihood ratios were 4.03 and 0.20. The rate of missed diagnosis was 15.7％, and the misdiagnosis rate was 20.9％. The total coincidence and Youden index were 81.1％ and 0.63. The area under ROC curve [95％ confidence interval (CI) ] was 0.855 (0.814 -0.896). When the daily mean of Cys C was 1.21 and 1.67 mg/L, the within-run coefficient of varication (CV) were 2.9％ and 2.7％, and the between-run CV were 3.6％ and 3.3％. The daytime CV were 4. 1％ and 3.8％, and the total CV were 7.0％ and 6.4％.Conclusions Serum Cys C has significant diagnosis value for early renal impairment in primary hypertension patients,and it is suitable for early screening.%目的 评价血清半胱氨酸蛋白酶抑制剂C(Cys C)对高血压患者早期肾损伤的诊断价值,为Cys C在临床的应用提供循证医学证据.方法 对318例原发性高血压并怀疑合并早期肾损伤的患者同时进行血清Cys C和99mTc-二乙三胺五醋酸(99mTc-DTPA)清除率的检测.以99mTc-DTPA清除率为诊断标准将318例患者分为肾损伤组(127例)和对照组(191例).用受试者工作特征(ROC)曲线选取血清Cys C诊断原发性高血压患者早期肾损伤的最佳临界点,计算敏感性、特异性、Youden指数等指标,评价血清Cys C诊断原发性高血压患者早期肾损伤的真实性.同时做血清Cys C检测的重复性试验,评价血清Cys C检测方法的可靠性.结果 根据ROC曲线,Cys C诊断原发性高血压患者早期肾损伤的最佳临界点为1.26 mg/L,其敏感性为84.3%、特异性为79.1%、阳性预测值为72.8%、阴性预测值为88.3%、阳性似然比为4.03、阴性似然比为0.20、漏诊率为15.7%、误诊率为20.9%、总符合率为81.1%、Youden指数为0.63、ROC曲线下面积[95%可信区间(CI)]为0.855(0.814～0.896).当Cys C日平均均值分别为1.21 、1.67 mg/ L 时,该法的批内变异系数(CV)分别为2.9%、2.7%,批间CV分别为3.6%、3.3%,日间CV分别为4.1%、3.8%,总CV分别为7.0%、6.4%.结论 血清Cys C对原发性高血压患者早期肾损伤有较好的诊断价值,尤其适合早期筛查.
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