Chen Jia, Chen Ke-Hong, Wang Li-Ming, Zhang Wei-Wei, Feng Lei, Dai Huan-Zi, He Ya-Ni
Department of Nephrology, Daping Hospital, Army Medical University, Chongqing 400042, China.
Department of Nephrology, Daping Hospital, Army Medical University, Chongqing 400042, China.
Clin Biochem. 2018 Aug;58:32-36. doi: 10.1016/j.clinbiochem.2018.06.001. Epub 2018 Jun 5.
Urinary DcR2 (uDcR2) is a biomarker for the early detection the tubulointerstitial injury (TII) in patients with chronic kidney disease (CKD), but the high-dose hook effect may lead to falsely low or even negative results when using an enzyme-linked immunosorbent assay (ELISA). This study aimed to investigate if the high-dose hook effect exists with ELISA testing, and to uncover a potential approach for reducing this effect.
72 CKD patients were recruited and categorized into four groups based on TII scores. uDcR2 was measured in undiluted and serially diluted (two-, four-, eight- and 16-fold dilutions) urine using an ELISA kit. The results from the assay were normalized to urinary creatinine. We evaluated the correlation between uDcR2/cre levels at different dilutions and renal histological parameters. Receiver operating characteristic (ROC) curves were generated to examine the value of uDcR2/cre for predicting TII.
uDcR2/cre levels in the undiluted urine were significantly higher in patients with CKD than those in the control. However, higher TII scores did not yield higher levels of uDcR2/cre in the undiluted urine. After serial dilution, uDcR2/cre levels were highest with the four-fold dilution. A positive correlation was found between uDcR2/cre levels at different dilutions and TII scores, with the highest correlation coefficient and the largest AUC being observed at the four-fold dilution.
The high-dose hook effect was apparent during ELISA testing of uDcR2 in CKD patients, yet dilution of the urine samples neutralized this effect. However, the use of a four-fold dilution of urine for uDcR2/cre testing may eliminate the high-dose hook effect and make it possible to effectively monitor the severity of TII in CKD patients.
尿诱饵受体2（uDcR2）是慢性肾脏病（CKD）患者肾小管间质损伤（TII）早期检测的生物标志物，但在使用酶联免疫吸附测定（ELISA）时，高剂量钩状效应可能导致结果假性降低甚至呈阴性。本研究旨在调查ELISA检测中是否存在高剂量钩状效应，并探索一种降低该效应的潜在方法。
招募72例CKD患者，根据TII评分分为四组。使用ELISA试剂盒检测未稀释及系列稀释（2倍、4倍、8倍和16倍稀释）尿液中的uDcR2。检测结果以尿肌酐进行标准化。我们评估了不同稀释度下uDcR2/肌酐水平与肾脏组织学参数之间的相关性。绘制受试者工作特征（ROC）曲线，以检验uDcR2/肌酐对预测TII的价值。
CKD患者未稀释尿液中的uDcR2/肌酐水平显著高于对照组。然而，在未稀释尿液中，较高的TII评分并未产生更高的uDcR2/肌酐水平。系列稀释后，4倍稀释时uDcR2/肌酐水平最高。不同稀释度下的uDcR2/肌酐水平与TII评分呈正相关，在4倍稀释时观察到最高的相关系数和最大的曲线下面积（AUC）。
在CKD患者uDcR2的ELISA检测过程中，高剂量钩状效应明显，但尿液样本稀释可中和该效应。然而，对uDcR2/肌酐检测采用4倍尿液稀释可能消除高剂量钩状效应，并有可能有效监测CKD患者TII的严重程度。
