Naz Saima, Ghafoor Farkhanda, Iqbal Imran Akhtar
1 National Health Research Complex, Shaikh Zayed Hospital, Lahore, Pakistan.
2 Department of Cardiology, Shaikh Zayed Hospital, Lahore, Pakistan.
Ann Clin Biochem. 2017 May;54(3):348-354. doi: 10.1177/0004563216662074. Epub 2016 Jul 15.
Background Myeloperoxidase has shown potential as a marker for prognosis of coronary artery disease, but presently little is known about preanalytical handling of samples for quantifying myeloperoxidase. The present study was conducted to evaluate the effect of collection tube and freeze-thaw cycles on myeloperoxidase concentrations. Methods Acute coronary syndrome patients ( n = 88) were enrolled after obtaining written informed consent from coronary care unit of a tertiary care hospital (January 2012-June 2014). About 5 mL venous blood was collected from patients and divided into serum, lithium heparin, ethylenediaminetetraacetic acid and sodium citrate tubes. Except serum, all tubes were kept on ice immediately after collection. Samples were centrifuged at -4℃, separated immediately after centrifugation and stored at -40℃ until analysis. Myeloperoxidase was quantified by in-house and commercial assays and re-quantified after five freeze-thaw cycles. Results Myeloperoxidase concentrations, (serum samples) determined by commercial and in-house assays correlated well (r = 0.946) ( P < 0.001) and were higher in serum samples. Within plasma, myeloperoxidase concentrations were slightly higher in ethylenediaminetetraacetic acid (307.7 ± 52.1) and lower in lithium heparin (290.3 ± 49.2) and sodium citrate (221.4 ± 40.3) but not statistically significant. Correlation between myeloperoxidase concentrations (in-house enzyme-linked immunosorbent assay) after first cycle and fifth freeze-thaw cycle dropped to r = 0.448 ( P < 0.001). Conclusion Myeloperoxidase concentrations are comparable in three types of plasma tubes when samples are placed on ice immediately, centrifuged at low temperatures and separated immediately after centrifugation. Multiple freeze-thaw cycles have an effect on myeloperoxidase and should be avoided for quantifying myeloperoxidase.
背景 髓过氧化物酶已显示出作为冠状动脉疾病预后标志物的潜力，但目前对于用于定量髓过氧化物酶的样本的分析前处理知之甚少。本研究旨在评估采血管和冻融循环对髓过氧化物酶浓度的影响。方法 在获得一家三级护理医院冠心病监护病房（2012年1月至2014年6月）的书面知情同意后，纳入急性冠状动脉综合征患者（n = 88）。从患者采集约5 mL静脉血，并分为血清管、肝素锂管、乙二胺四乙酸管和枸橼酸钠管。除血清管外，所有采血管在采集后立即置于冰上。样本在-4℃离心，离心后立即分离，并在-40℃保存直至分析。通过内部检测和商业检测对髓过氧化物酶进行定量，并在五个冻融循环后重新定量。结果 商业检测和内部检测所测定的髓过氧化物酶浓度（血清样本）相关性良好（r = 0.946）（P < 0.001），且血清样本中的浓度更高。在血浆中，乙二胺四乙酸管中的髓过氧化物酶浓度略高（307.7±52.1），肝素锂管（290.3±49.2）和枸橼酸钠管（221.4±40.3）中的浓度较低，但无统计学意义。第一个循环和第五个冻融循环后髓过氧化物酶浓度（内部酶联免疫吸附测定）之间的相关性降至r = 0.448（P < 0.001）。结论 当样本立即置于冰上、在低温下离心并在离心后立即分离时，三种类型的血浆管中的髓过氧化物酶浓度相当。多个冻融循环对髓过氧化物酶有影响，在定量髓过氧化物酶时应避免。
