Objective To investigate the practical application of the interference screening and quantification for urine analysis in clinical chemistry according to the Clinical and Laboratory Standards Institute ( CLSI) EP7-A2 document, and evaluate the interference effects of aminoglycoside antibiotic in urine total protein determination. Methods According to the CLSI EF7-A2 document, fresh urine specimens with the urine total protein concentrations of 77, 146, 538 and 832 mg/L were collected, and the etimicin sulfate solution of 3 times maximum therapeutic dosage per liter of urine was added. The interference was screened by pyrogallol red-molybdale assay. The interference effects were quantified, and the etimicin sulfate solution and distilled water were added to form a concentration gradient (0, 0. 15, 0.30, 0. 45 and 0. 60 mg/mL) of the interferent for each group. By multiple regression analysis, the degrees of interference at any inierferent concentrations were estimated. Results After adding 0. 6 mg/mL of etimicin sulfate solution into 4 groups (with the arine total protein concentrations of 77, 146, 538and832 mg/L), the lower confidence limit of interference effect exceeded the allowable error at (he medical decision concentration. Adding 5 concentrations of the etimicin sulfale solution into each specimen group, the five-level dose-response series (0, 0.15, 0.30, 0.45 and 0.60 mg/mL) all showed a linear relationship, and the linear equations were Y = 202X-1.2,Y=187.3X+4,Y= 325. 3X + 0.6 and Y=345. 3X +6.4. It indicated that the positive interference effects caused by etimicin sulfate while adding0.08,0.15,0.35 and 0.50 mg/ml of the interferent into each urine group, all exceeded the allowable error. Conclusions The etimicin sulfate causes a positive interference in the pyrogallol red-molybdale assay for urine total protein determination. Clinical laboratories need to perform the interference tests to screen potential interferents, quantify interference effects, evaluate potential hazards and establish meaningful interference claims.%目的 探讨美国临床实验室标准化协会( CLSI) EP7-A2文件对于筛查、量化临床化学尿液样本分析干扰的实际应用,评价氨基糖苷类抗菌药物对尿总蛋白检测的干扰效应.方法 遵循CLSI EP7-A2文件,选取尿总蛋白浓度为77、146、538、832 mg/L的新鲜尿液样本,分别加入最大治疗剂量时每升尿液中3倍浓度的硫酸依替米星溶液,采用邻苯三酚红钼法分别进行干扰筛选试验.4种浓度尿液样本中分别加入由硫酸依替米星和一级纯水配制而成的梯度浓度溶液(0、0.15、0.30、0.45、0.60 mg/mL),进行干扰效应试验.通过多项式回归分析量化干扰效应,估计在任何干扰物浓度水平下的干扰度.结果 在尿总蛋白浓度分别为77、146、538、832 mg/L的尿液样本中加入0.6 mg/mL硫酸依替米星溶液,其干扰效应点估计值置信区间下限均超过医学决定水平处的允许误差.在尿总蛋白浓度分别为77、146、538、832 mg/L的尿液样本中加入5个干扰浓度(0、0.15、0.30、0.45、0.60 mg/mL)的硫酸依替米星溶液,得出的系列浓度均为线性剂量效应关系,其线性方程分别为Y=202X - 1.2、Y=187.3X+4、Y=325.3X+0.6、Y=345.3X +6.4.通过回归方程分析得出尿总蛋白浓度为77、146、538、832 mg/L时,加入0.08、0.15、0.35、0.50 mg/mL硫酸依替米星溶液所引起的正干扰效应均超过临床可接受的允许误差.结论 硫酸依替米星对邻苯三酚红钼法测定尿总蛋白存在正干扰；临床实验室需进行分析干扰实验,筛选潜在干扰物质,量化干扰效应、评估潜在风险,并建立对临床有意义的干扰声明.
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