检测原发性肾病综合征患儿尿足细胞标志蛋白的临床意义

Clinical significance of determining urinary podocalyxin level in children with primary nephrotic syndrome

摘要:

目的：探讨检测尿液中足细胞标志蛋白podocalyxin(PCX)在儿童原发性肾病综合征（PNS）的临床诊断及病情评估中的作用。方法：采用透射比浊法对175例儿童晨尿PCX的表达水平进行检测，其中包括未经治疗的PNS患儿（活动期组）53例（单纯型肾病36例、肾炎型肾病17例）、PNS完全缓解期患儿（缓解组）56例(复发者42例，非复发者14例)、健康儿童66例（对照组）。测定53例PNS活动期患儿同期24 h尿蛋白的水平；绘制ROC曲线，确定尿PCX诊断PNS活动期及鉴别肾炎型肾病的最佳临界点。结果：活动期组与缓解组及对照组比较，尿PCX水平明显升高（P<0.01）。活动期组尿PCX水平与24 h尿蛋白水平呈正相关（r=0.39，P<0.01）。活动期组患儿中，肾炎型肾病患儿较单纯型肾病患儿尿PCX水平升高，差异有统计学意义（P<0.01）。缓解组中，复发者尿PCX水平较非复发者高，差异有统计学意义（P<0.05）。尿PCX诊断PNS活动期及肾炎型肾病的 ROC曲线下面积分别为0.915、0.784；诊断临界点分别为7.97 ng/mL、10.28 ng/mL，灵敏度分别为81.1％、94.1％，特异度分别为93.4％、52.8％。结论：利用PCX定量检测可动态观察尿足细胞的变化，对判断肾小球的损伤程度及疾病的活动情况、临床鉴别单纯型肾病与肾炎型肾病有一定的意义。

Abstract:

OBJECTIVE: To study the clinical significance of urinary podocyte marker protein podocalyxin (PCX) in the diagnosis of primary nephrotic syndrome (PNS) in children and the evaluation of disease severity. METHODS: PCX levels in the first morning urine were measured by turbidimetric immunoassay (TIA) in 175 children, including 53 children with acute PNS［36 cases of simple nephrotic syndrome (NS) and 17 cases of nephritic NS］, 56 children with PNS in the remission stage (relapsed: 42 cases) and 66 healthy children (control group). Twenty-four hour urinary protein was measured in the 53 children with acute PNS. The optimal operating points for the diagnosis of acute PNS and nephritic NS were determined using the receiver-operating characteristic curve (ROC curve). RESULTS: Significant increasd levels of urinary PCX were found in children with acute PNS compared with those in the remission stage and the control group (P<0.01). A positive correlation was found between urinary PCX and 24 hour urinary protein in children with acute PNS (r=0.39, P<0.01). In children with acute PNS, urinary PCX levels were significantly higher in the nephritic NS group than in the simple NS group (P<0.05). In children in the remission stage, a significant increase in levels of urinary PCX was found in children who had relapsed compared with those who had not (P<0.05). The area under the ROC curve for the diagnosis of acute PNS and nephritic NS was 0.915 and 0.784 respectively. The optimal operating point for the diagnosis of acute PNS and nephritic NS was 7.97 and 10.28 ng/mL respectively, with a sensitivity and specificity of 81.1% and 93.4% respectively for acute PNS and of 94.1% and 52.8% respectively for nephritic NS. CONCLUSIONS: The quantitative detection of urinary PCX is useful in the evaluation of podocyte dynamic changes. It is helpful in the diagnosis of acute PNS and in the differentiation of nephritic NS and simple NS.