Storage temperature and differing methods of sample preparation in the measurement of urinary albumin

Summary Microalbuminuria is a predictor of persistent proteinuria, renal failure and cardiovascular disease and therefore accurate determination of urinary albumin concentration is important. We examined the stability of albumin in urine under different conditions of storage, temperature and sample preparation. There was no significant difference in urinary albumin concentration between fresh urine and urine stored at either 4°C or 20°C for up to 7 days. Similarly in urine samples from diabetic patients there was no significant difference in albumin concentration at levels ranging from 1.3 to 1999.3 mg/l between fresh urine at 4°C and urine stored frozen for 1 week, 1 month or 6 months. Neither storage temperature (−20°C or −40°C) nor centrifugation of sample prior to assay made a significant difference to the albumin concentration. Multiple freezing and thawing of urine samples during 6 weeks of storage at −20°C made no difference to albumin concentrations. Storage of urine samples in either polypropylene, polystyrene or borosilicate glass tubes did not result in a significant change in urinary albumin concentration after either 1 week or 1 month at −20°C although, after 1 month of storage, urinary albumin concentrations tended to be lower by an average of approximately 7%. In tubes to which gelatine had been added this was reduced to 4%. We conclude that fresh urine can be kept at 4°C or 20°C for up to 7 days. Frozen urine samples can be stored for up to 6 months before assay without any loss of albumin concentration. Polypropylene, polystyrene or borosilicate glass tubes are acceptable containers for short-term storage and samples can simply be thoroughly thawed and vortex mixed immediately prior to assay.     

免疫比浊法用于全自动生化分析仪中产生钩状效应的防范

目的正确认识免疫透射比浊法应用于全自动生化分析仪上的抗原过量产生的钩状效应及对这种钩状效应的防范。方法首先对仪器的测量线性范围上限和仪器自动稀释重做功能进行设置,然后对设置前超过测量范围上限的样本进行设置测定及设置前且人工对倍稀释测定。结果设置前测定组平均值为2.49g/L设置后测定组平均值为3.31g/L设置前且人工对倍稀释测定组平均值为3.33g/L。结论高剂量钩状效应使强阳性标本误测为弱阳性,甚至假阴性结果,高浓度标本误测为低值,所以对仪器进行设置且对标本倍比稀释来进行测定,测出来的值更接近真值。     

C 反应蛋白快速定量检测试剂盒性能评价

目的：评价以胶乳免疫比浊法原理研制的C反应蛋白快速定量检测试剂盒的方法学性能。方法测定试剂盒的检测限、精密度、线性范围、回收率、贮存稳定性,将检测200份样本的结果与国外试剂盒比较。结果检测限为0．72 mg/L,精密度：高、低浓度水平的样本批内变异系数分别为3．09％、6．75％,批间变异系数分别为6．47％、6．84％;线性范围为1～215 mg/L,线性相关系数为0.99;平均回收率为112．5％,系统误差＜1/2TEa。贮存有效期：18个月。200份不同浓度样本测定结果与进口试剂盒比较差异无统计学意义。结论研制的C反应蛋白快速定量检测试剂盒符合临床检测要求。     

参照C28-A2确定胱抑素C的参考值范围

目的建立本实验室胱抑素C（胱氨酸蛋白酶抑制剂,Cytatin C,Cys-C）免疫透射比浊法测定试剂盒的参考值范围。方法随机抽取240例健康人员的新鲜血清,利用市售胱抑素C测定试剂盒（免疫透射比浊法）进行测定,测定结果按CLSIC28-A2（临床实验室参考值范围的定义和确认．第2版）进行统计处理。结果本实验室1～49岁健康人群胱抑素C参考值范围为0．59—1．06mg／L,50-88岁健康人群胱抑素C参考值范围为0．48～1．32mg／L。结论实验室有．必要根据CLSIC28-A2文件的规定建立自己的参考值范围。     

载脂蛋白A1与结直肠肿瘤恶性度的相关研究

目的研究载脂蛋白A1（apolipoprotein A1,APOA1）在结直肠息肉、不同分级分期及远处转移的结直肠癌患者血清中的表达,旨在探讨APOA1与结直肠肿瘤恶性度的相关性。方法收集59位结直肠肿瘤患者血清,由病理学医师根据肿瘤细胞浸润及分化程度进行分期及分级,并对是否伴随远处转移进行分类。本实验采用蛋白免疫印迹法与免疫比浊法对APOA1的表达进行分析。结果 APOA1在低分化结直肠癌患者血清与息肉、高分化及中分化血清相比表达量减少（P=0.035,P=0.028,P=0.028）,APOA1在结直肠息肉血清中的表达量与不同分期及远处转移的结直肠癌血清中的表达比较,差异无统计学意义（P〉0.05）。结论 APOA1与结直肠肿瘤的分级存在相关性,对不同恶性度的结直肠肿瘤患者可发挥肿瘤标志物的作用。     

Contents of apolipoprotein A-I,A-II and B of the human serum fractions for high-density and low-density lipoproteins prepared by common precipitation methods

Two common precipitation methods for the determination of HDL-cholesterol in human serum were used, dextran sulphate/MgCl₂ and phosphowolframate/MgCl₂. They yield supernatants which contained almost all of the apoA-I and apoA-II lipoproteins but no lipoprotein apoB. The correlations between chol-HDL and apoA-I were about the same with these methods (r=0.79 and 0.80). The correlation between the precipitation methods and ultracentrifugal analysis for chol-HDL was highly significant (r=>0.95). Correspondingly, two common precipitation methods for the determination of LDL-cholesterol in human serum, buffered heparin, and polyvinyl sulphate procedures, produced sediments, which contained the major proportion of the apoB and only small amounts of apoA-I and apoA-II. However, yields of only 69.0–80.2% were obtained for apoB from the sediments and of 85.8–89.4% from supernatants calculated as the difference from chylomicron free serum. This difference might be due to alterations of the molecular structure of apoB by the precipitation reagents. Comparison of the results with the precipitation methods to those using the Friedewald formula showed excellent agreements (r=>0.91). Very comparable results were also obtained in the case of marked hypertriglyceridaemia provided that the serum samples were briefly centrifuged before analysis of chol, chol-HDL, and triglyceride values for the formula of chol-LDL. The precipitation methods for chol-LDL showed very good agreement with the values obtained by ultracentrifugal analysis (r=>0.93). There were no remarkable differences in the correlation of apoB and chol-LDL values measured by different methods (r=0.85).

According to the present results it was found that highly significant correlations existed between chol/chol-HDL or chol-LDL/chol-HDL and apoB/apoA-I ratios (p < 0.001). It is quite evident that apoB and apoA-I values could be used to replace chol-LDL and chol-HDL values when the risk for the cardiovascular diseases is to be assessed.     

免疫比浊法检测糖化血红蛋白A1c的性能评价

目的评价Roche公司第3代免疫比浊法检测糖化血红蛋白A1c(HbA1c)的性能。方法分析免疫比浊法检测HbA1c的精密度、线性,评价Hb、胎儿Hb(HbF)、三酰甘油(TG)、总胆红素(T-Bil)和不稳定HbA1c对HbA1c检测的影响、抗干扰能力及其与HPLC法测HbA1c结果的相关性;比较免疫比浊法检测HbA1c与高效液相色谱(HPLC)法的一致性。结果免疫比浊法检测HbA1c的变异系数(CV)均<2.5%。在4.7%～15.4%范围内,理论值与实测均值呈线性相关,r2值达0.999。Hb、HbF、T-Bil、TG水平分别在57～177 g/L、1.7%～11.7%、27～265μmol/L、3.2～9.85 mmol/L范围时,差异百分比均<5%;当HbF>13.5%时,差异百分比>5%。不稳定GHb(样本葡萄糖糖含量0～55.56 mmol/L)对HbA1c检测无影响。免疫比浊法(X)与高效液相色谱法(Y)相关性良好,Y=1.0188X-0.2271,r2=0.971 3。结论免疫比浊法检测HbA1c性能良好,适合临床应用。     

广州地区健康成年人血清铁蛋白参考区间的建立

目的 了解广州地区健康成人血清铁蛋白水平,建立本地区血清铁蛋白的正常参考值范围。方法 收集中山大学孙逸仙纪念医院2019年2月~9月参加体检的健康成人286例,男132例、女154例,按照性别、年龄将受检对象分为6组,分别为男、女青年组（18~39 岁）,男、女中年组（40~59岁）,男、女老年组（≥60 岁）。通过描绘血清铁蛋白水平直方图,应用Kolmogorov-Smirno方法进行正态性检验,对偏态分布的数据通过百分位数法求出双侧95%可信区间作为正常参考值范围。结果 健康成人血清铁蛋白水平呈偏态分布,男性和女性的正常参考值范围分别为50.3~462.3 μg/L和4.5~358.6 μg/L;男性青年、中年、老年的正常参考值范围分别为46.3~450.5 μg/L;56.5~441.3 μg/L;60.8~465.2 μg/L;女性青年、中年、老年的正常参考值范围分别为3.5~209.4 μg/L;4.0~362.5 μg/L;21.0~383.8 μg/L。结论 广州地区健康男性和女性血清铁蛋白的正常参考值范围存在较大差异,且与厂家说明书提供的参考值范围差别较大,各地区、各实验室有必要按性别、年龄建立适合本地区的血清铁蛋白参考值范围。     

免疫比浊法测定抗环瓜氨酸肽抗体的临床应用

目的 评价免疫比浊法检测抗环瓜氨酸肽抗体(CCP)在类风湿关节炎(RA)诊断中的临床价值。方法 收集195例RA、105例骨关节炎、52例骨质疏松、42例结缔组织、40例系统性红斑狼疮、305例其他疾病患者,以及90例健康对照者的血清标本,分别使用免疫比浊法(Latex)、化学发光微粒子免疫法(CMIA)、酶联免疫吸附试验法(ELISA)检测CCP并比较结果。结果 Latex法检测RA阳性141例(72.30%),关节炎阳性54例(51.42%),骨质疏松阳性15例(28.84%),结缔组织阳性15例(35.71%),系统性红斑狼疮阳性18例(45.0%),其他疾病阳性11例(3.60%),90例健康对照者均为阴性。批内变异系数为1.9%~2.0%,总变异系数为2.0%~2.1%,Latex法试剂线性范围为0.8~100U/mL。Latex法、CMIA法、ELISA法检测CCP的敏感性和特异性差异无统计学意义(P0.05)。结论 Latex法检测CCP的敏感性和特异性好,线性范围宽,可用于临床。