胱抑素C及其eGFR方程在诊断肝硬化患者肾损害中的应用

Clinical Application of Cystatin C and It’s eGFR Equation for Diagnosing Kidney Injure in Patients with Liver Cirrhosis

目的 探讨血清胱抑素C（cystatin C,CysC）及其估算肾小球滤过率（estimated glomerular filtration rate,eGFR）方程在肝硬化患者肾功能损害中的诊断价值。方法 随机抽取2012年8月-2014年12月间来绵阳市中心医院就诊的肝硬化患者465例,检测其血清肌酐（serum creatinine,SCr）和CysC水平,并采用适用于中国人群的方程计算其相应的eGFR,即eGFRSCr和eGFRCysC。继而用ROC曲线分析此四个标志物对肝硬化患者继发肾功能损害的诊断性能,并与SCr和CysC参考值上限（upper reference limit,UPL）及eGFR医学决定水平（medicine decide level,MDL）作为判断界点进行比较。结果 SCr（男/女）,CysC,eGFRSCr和eGFRCysC对肝硬化患者肾功能损害的最佳判断线分别是76.8 μmol/L（男）,62.6μmol/L（女）,1.24 mg/L,109.9 ml/min/1.73m^2和63.4 ml/min/1.73 m^2; ROC曲线分析显示,CysC及其eGFRCysC的AUC均高于SCr及其eGFRSCr的AUC（z=3.660-5.387,P〈0.001）; 比较四者在最佳判断线和UPL/MDL两个判断界点间的诊断性能,在肝硬化及其Child-Pugh分级患者各组中,仅eGFRCysC的敏感度、误诊率和临床诊断一致性均相接近（除误诊率外,P〉0.05）。结论 eGFRCysC对肝硬化患者继发肾功能损害的诊断性能优于CysC,SCr和eGFRSCr。但因其并非实测,故各实验室应建立自己的最佳判断线。临床医生应用eGFR评价受试者肾功能,而非局限于其分析物浓度。

Objective To investigate the diagnostic efficiency of Cystatin C（CysC） and it＇s eGFR equation for diagnosis of kidney impairment in patients with liver cirrhosis. Methods A total of 465 liver cirrhosis patients were enrolled in this study,which admitted to Mianyang Central Hospital between Aug. 2012 to Dec. 2014. Serum creatinine （SCr） and CysC level were determined,and to be used to calculate their corresponding estimated glomerular filtration rate （eGFR） by the equations suitable for chinese patients,namely eGFRscr and eGFRcysc. The performance of these four markers to diagnose kidney impairment in liver cirrhosis patients were analyzed by ROC curve method, and to compare with those when the upper refer- ence limits （UPL） of SCr and CysC,and the medicine decide level （MDL） of eGFR,as a threshold. Results The optimal cut-off values of SCr （male or female）,CysC,eGFRscr and eGFRcysc for diagnosing kidney impairment in liver cirrhosis patients were 76.8 μmol/L （male） ,62.6 μmol/L （female） ,1.24 mg/L,109.9 ml/min/1.73 m^2 and 63.4 ml/min/1.73 m^2 ,respectively. The AUC of both CysC and eGFRcysc were higher than SCr or eGFRscr （z = 3. 660-5. 387, P〈0. 001）. Compa- ring the performance of the four on the two thresholds of optimal cut-off value and UPL/MDL,only eGFRcysc ,it was sensi- tivity,misdiagnosis rate and consistency were similar to each other （except misdiagnosis rate, P〉0.05）, whether in patients- with cirrhosis or various subgroups by Child-Pugh classifications. Conclusion eGFRcysc was a better marker than CysC,SCr and eGFRscr for diagnosing secondary kidney impairment in patients with cirrhosis. Due to not measurements, each clinical laboratory should establish its own optimal cut-off values. Clinicians should assess renal function with eGFR rather than the concentration of an analytes.