目的 探讨尿液血管紧张素转换酶2（angiotensin-converting enzyme 2，ACE2）和配对盒基因2（paired box gene 2，PAX2）蛋白在先天性肾脏及尿路畸形（congenital anomalies of the kidney and urinary tract，CAKUT）患儿中的表达水平及其与急性肾损伤（acute kidney injury，AKI）的关联，评估二者作为CAKUT早期肾损伤生物标志物的诊断价值。 方法 纳入266例CAKUT患儿（年龄1 ~ 18岁），根据KDIGO标准分为CAKUT合并AKI组（n = 68）和CAKUT无AKI组（n = 198），并匹配健康对照组（n = 45）。采用酶联免疫吸附法检测晨尿中ACE2和PAX2水平，结合肾功能指标（血肌酐、eGFR等）进行统计学分析。通过ROC曲线评估诊断效能，Pearson相关分析探究标志物与eGFR的相关性。 结果 CAKUT合并AKI组尿ACE2和PAX2水平显著高于CAKUT无AKI组及健康组，且随AKI分期加重呈阶梯式上升（P < 0.01）。CAKUT无AKI组与健康对照组间差异无统计学意义（P > 0.05）。ACE2和PAX2均与eGFR呈负相关（r = -0.72，P < 0.01；r = -0.805，P < 0.01）。ACE2单独诊断AUC为0.917（截断值177.8 ng/mg Cr，敏感度80.9%，特异度86.4%）；PAX2单独诊断AUC为0.853（截断值11.1 pg/mg Cr，敏感度80.3%，特异度76.1%）；联合检测AUC提升至0.956（敏感度88.2%，特异度87.9%），显著优于单一指标（P < 0.01）。 结论 尿液ACE2与PAX2可用于辅助诊断CAKUT并发急性肾损伤，且诊断效能良好。

Objective To investigate the expression levels of urinary ACE2 and PAX2 proteins in children with congenital anomalies of the kidney and urinary tract （CAKUT） and their association with acute kidney injury （AKI）， and to assess the diagnostic value of these proteins as biomarkers for early renal injury in CAKUT. Methods A total of 266 children aged 1 ~ 18 years with CAKUT were enrolled. They were divided into the CAKUT with AKI group （n = 68） and the CAKUT without AKI group （n = 198） in accordance with the Kidney Disease： Improving Global Outcomes （KDIGO） criteria， along with a matched healthy control group （n = 45）. The levels of angiotensin-converting enzyme 2 （ACE2） and paired box 2 （PAX2） in morning urine were measured by means of enzyme-linked immunosorbent assay （ELISA）. Statistical analysis was carried out in combination with renal function indicators such as serum creatinine and estimated glomerular filtration rate （eGFR）. The diagnostic efficacy was assessed via receiver operating characteristic （ROC） curve analysis， and the correlation between the markers and eGFR was investigated using Pearson correlation analysis. Results The levels of urinary ACE2 and PAX2 in the CAKUT-AKI group were significantly higher compared to those in the non - AKI group and the healthy group， and they exhibited a stepwise increase as the AKI stages progressed （P < 0.01）. There was no statistically significant difference between the non - AKI group and the healthy group （P > 0.05）. Both ACE2 and PAX2 demonstrated strong negative correlations with eGFR （r = -0.72， P < 0.01； r = -0.805， P < 0.01）. The area under the curve （AUC） for ACE2 alone in diagnosis was 0.917 （cut-off value 177.8 ng/mg Cr， sensitivity 80.9%， specificity 86.4%）； the AUC for PAX2 alone in diagnosis was 0.853 （cut-off value 11.1 pg/mg Cr， sensitivity 80.3%， specificity 76.1%）； the combined testing AUC increased to 0.956 （sensitivity 88.2%， specificity 87.9%）， which was significantly superior to single indicators （P < 0.01）. Conclusion Urinary ACE2 and PAX2 can be utilized to aid in the diagnosis of CAKUT complicated by acute kidney injury， demonstrating favorable diagnostic efficacy.