Effects of Cold Agglutinin on the Accuracy of Complete Blood Count Results and Optimal Sample Pretreatment Protocols for Eliminating Such Effects

摘要

Dear Editor, Cold agglutinin is an autoantibody that causes autoimmune hemolytic anemia by binding to I/i carbohydrate antigens on the red blood cell (RBC) surface [ 1 ]. While RBC agglutination causes clinical symptoms of hemolytic anemia, agglutination caused by cold agglutinin is a notorious pre-analytical and analytical factor that leads to spurious automated complete blood count (CBC) results [ 2 ]. Although RBC agglutination falsely increases mean corpuscular volume (MCV), effects of cold agglutinin on other CBC parameters have not been widely studied [ 3 , 4 ]. The effects of cold agglutinin on CBC results have been evaluated mainly for a limited number of parameters, on old versions of automated CBC analyzers [ 5 , 6 ], which have undergone remarkable technical improvements in the last decade. We present a case of chronic cold agglutinin disease, and report the effects of cold agglutinin on CBC parameters based on whole blood samples comparatively analyzed by four automated CBC analyzers commonly used in current clinical laboratories. A 56-year old male patient visited our hospital for low hemoglobin (Hb) concentration, fatigue, and hematuria. The initial CBC results revealed the following: Hb, 102 g/L; platelets, 275×109/L; and white blood cell (WBC) count, 4.70×109/L. Peripheral blood smear showed normocytic normochromic anemia with mild anisopoikilocytosis, mild elliptocytosis, and dacryocytes. RBC clumps that resolved after sample incubation at 37℃ suggested the diagnosis of cold agglutinin disease. The patient required no specific treatment because symptoms were not severe. Follow-up seasonal variations in symptoms and CBC results were observed. The institutional review board of National Health Insurance Service Ilsan Hospital approved this study (IRB number: NHIMC 2015-03-011). In total, 16 K2EDTA samples of whole blood were collected. The first sample was analyzed on the XE-2100 (Sysmex, Kobe, Japan) immediately after collection, the results of which served as reference values. The four most commonly used automated CBC analyzers—XE-2100, XN-1000 (Sysmex), ADVIA 2120i (Siemens Diagnostics, Tarrytown, NY), and Unicel DxH 800 (Beckman Coulter Inc., Fullerton, CA)—were used for comparative analysis. The experimental flowchart is shown in Fig. 1A . Each automated CBC analyzer measured four samples. System accuracy was compared using the unit of delta percentage difference (DPD) from the reference value, which was defined according to a previous report [ 7 ] as follows: D e l t a P e r c e n t a g e D i f f e r e n c e ( % ) = ( T e s t a n a l y z e r t e s t t u b e ? r e f e r e n c e a n a l y z e r r e f e r e n c e t u b e ) R e f e r e n c e a n a l y z e r r e f e r e n c e t u b e × 100 We analyzed the effects of analyzer type, storage temperature, storage duration, and incubation period, using eight CBC parameters [RBC count, Hb, hematocrit, MCV, mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), WBC count, and platelet count] in terms of DPD. We interpreted the results as positive or negative bias, or acceptable. The criteria for spurious effects were derived from three guidelines for quality requirements for automated CBC analyzers ( Table 1 ) [ 8 , 9 , 10 ]. When we compared three temperature conditions [i.e., measurements (1) or (2), (3), and (4) in Fig. 1A , according to analyzer], the sample stored for 1 hour at 37℃ showed the smallest deviance from the reference value based on the DPD value ( Fig. 1B , Table 1 ). Interestingly, Hb concentration and platelet count were not highly affected by storage temperature, while WBC count showed variability according to the analyzer used. For all analyzers, except the XN-1000, sample storage at 37℃ for 1 hour yielded more accurate results than storage at 37℃ for 24 hours. When we compared samples stored at 37℃ for 1 hour with samples stored at 4℃ for 1 hour followed by incubation at 37℃ for 1 hour, there was no significant difference in any of the parameter values ( Fig. 1C ). Based on these results, we propose two practically optimal protocols: (1) measuring CBC within 1 hour if the sample is stored at 37℃ after collection and (2) measuring CBC after incubation at 37℃ for 1 hour if the sample is stored at 4℃ for a short term. An interesting finding of our study was that Hb concentration showed the smallest variance among all parameters evaluated in this study. This finding is consistent with those of previous studies [ 2 , 3 ] and is likely owing to the fact that we measured Hb after RBC lysis, which eliminates clumping by cold agglutinin. From a clinical aspect, it is reassuring that the most important variable for determining the need for RBC transfusion is not substantially distorted by the presence of cold agglutinin. Thus, we demonstrated spurious effects of cold agglutinin on eight parameters comparatively measured on four automated CBC analyzers. Our results indicated that cold agglutinin affects not

机译：亲爱的编辑，凝集素是一种自身抗体，通过与红细胞（RBC）表面的I / i碳水化合物抗原结合而引起自身免疫性溶血性贫血[1]。尽管RBC凝集会引起溶血性贫血的临床症状，但冷凝集素引起的凝集是一个臭名昭著的分析和分析因素，会导致虚假的自动全血细胞计数（CBC）结果[2]。尽管RBC凝集错误地增加了平均红细胞体积（MCV），但冷凝集素对其他CBC参数的影响尚未得到广泛研究[3，4]。冷凝集素对CBC结果的影响主要在有限数量的参数上进行了评估，在旧版本的自动CBC分析仪上[5，6]进行了评估，在过去的十年中，这些分析仪进行了显着的技术改进。我们介绍了一个慢性冷凝集素疾病病例，并基于全血样本报告了冷凝集素对CBC参数的影响，全血样本是由目前临床实验室中常用的四种自动CBC分析仪进行比较分析的。一名56岁的男性患者因血红蛋白（Hb）浓度低，疲劳和血尿而去我院。最初的CBC结果显示：Hb，102 g / L;血小板275×109 / L;白细胞计数为4.70×109 / L。外周血涂片显示正常血红细胞正常性贫血，伴轻度异嗜单核细胞增多症，轻度椭圆细胞增多症和红细胞。样品在37℃孵育后红细胞团块溶解，提示诊断为冷凝集素疾病。由于症状不严重，患者无需特殊治疗。观察到症状和CBC结果的后续季节性变化。国民健康保险服务一山医院的机构审查委员会批准了本研究（IRB号：NHIMC 2015-03-011）。总共收集了16个K2EDTA全血样品。收集后立即在XE-2100（Sysmex，神户，日本）上分析第一个样品，其结果用作参考值。使用了四种最常用的自动CBC分析仪-XE-2100，XN-1000（Sysmex），ADVIA 2120i（Siemens Diagnostics，Tarrytown，NY）和Unicel DxH 800（Beckman Coulter Inc.，Fullerton，CA）进行比较。分析。实验流程图如图1A所示。每个自动CBC分析仪都测量了四个样品。使用与参考值的差值百分比差异（DPD）单位比较系统精度，该差值根据先前的报告[7]定义如下：德尔塔百分比百分比差异（％）=（T estanalyzertesttube？referenceanalyzerrefe rencetube） R eferenceanalyzerreferencetube×100我们使用八种CBC参数[RBC计数，Hb，血细胞比容，MCV，平均红细胞血红蛋白（MCH），平均红细胞血红蛋白浓度（MCHC），分析了分析仪类型，存储温度，存储时间和潜伏期的影响），WBC计数和血小板计数]。我们将结果解释为正偏差或负偏差，或可以接受。杂散效应的标准来自对自动CBC分析仪质量要求的三项准则（表1）[8、9、10]。当我们比较三个温度条件（即根据分析仪，在图1A中的测量值（1）或（2），（3）和（4））时，在37℃下保存1小时的样品与参考值基于DPD值（图1B，表1）。有趣的是，Hb浓度和血小板计数不受存储温度的影响很大，而根据所使用的分析仪，WBC计数显示出可变性。对于所有分析仪，除XN-1000以外，在37℃下保存1小时的样品比在37℃下保存24小时的结果更为准确。当我们将在37℃下保存1小时的样品与在4℃下保存1小时然后在37℃下孵育1小时的样品进行比较时，任何参数值都没有显着差异（图1C）。根据这些结果，我们提出了两种实用的最佳方案：（1）如果样品收集后在37℃下保存，则在1小时内测量CBC;（2）如果样品在37℃下孵育1小时，则在1小时内测量CBC。短期为4℃。我们研究的一个有趣发现是，在本研究评估的所有参数中，血红蛋白浓度显示出最小的方差。这一发现与先前的研究[2，3]一致，并且可能是由于我们在RBC裂解后测量了Hb，从而消除了冷凝集素造成的结块。从临床的角度来看，可以确定的是，确定冷血凝集素的存在不会严重扭曲确定RBC输血需要的最重要变量。因此，我们展示了冷凝集素对在四个自动CBC分析仪上相对测量的八个参数的虚假影响。我们的结果表明冷凝集素不影响

Effects of Cold Agglutinin on the Accuracy of Complete Blood Count Results and Optimal Sample Pretreatment Protocols for Eliminating Such Effects

摘要

著录项

相似文献

相关主题

期刊订阅