Department of Laboratory Medicine, University-Hospital of Padova, Padova, Italy.
Department of Medicine-DIMED, University of Padova, Padova, Italy.
Int J Lab Hematol. 2019 Dec;41(6):772-777. doi: 10.1111/ijlh.13108. Epub 2019 Sep 11.
Lipemia in samples can cause analytical errors in coagulation tests using photometric assays. To define the level of this interference, some studies assessed lipemic interferences by in vitro 'spiking' of different types of lipids obtaining interesting information, but spiked samples do not represent a real-world situation as natively lipemic samples do.
A total of 101 samples flagged as 'lipemic' by a Sysmex CS-5100 coagulometer were analyzed for PT, aPTT, fibrinogen Clauss assay, antithrombin activity, D-dimer concentration, before and after a double high-speed centrifugation procedure to reduce lipemic interference. We evaluated using Bland-Altman test if high-speed centrifugation and retesting are justified, considering that's a resource-consuming procedure; when a statistically significant difference was found, quality specification for imprecision was considered and compared to the observed delta.
Statistically significant differences were found for PT, antithrombin activity and fibrinogen. Considering the Bland-Altman plot, fibrinogen results were split into two groups, and statistically significant difference was confirmed only for samples >2 g/L.
For PT and antithrombin activity a mean percentual difference between the two determinations lower than within-subject biologic variation and one of the Fraser's quality specifications can be considered as a confounding 'noise' factor that is neither analytically nor clinically relevant. If the instrument determines a result on the first run, for PT, aPTT, D-dimer concentration and antithrombin activity tests, the double plasma high-speed centrifugation is unnecessary. It is instead necessary if fibrinogen >2 g/L or if the instrument cannot determine a result on the first run.
脂血样本会导致使用光电比浊法检测的凝血试验出现分析误差。为了确定这种干扰的程度，一些研究通过体外“添加”不同类型的脂质来评估脂血干扰，从而获得了一些有趣的信息，但添加样本并不能代表实际情况，因为它们与天然脂血样本不同。
对 101 份被希森美康 CS-5100 凝血仪标记为“脂血”的样本进行 PT、APTT、纤维蛋白原 Clauss 测定、抗凝血酶活性、D-二聚体浓度检测，在进行两次高速离心以减少脂血干扰之前和之后。我们使用 Bland-Altman 检验来评估高速离心和重新检测是否合理，因为这是一个资源消耗的过程；当发现统计学上的显著差异时，我们考虑了不精密度的质量规范，并将其与观察到的差值进行了比较。
PT、抗凝血酶活性和纤维蛋白原的检测结果存在统计学显著差异。考虑到 Bland-Altman 图，纤维蛋白原的结果分为两组，仅对于 >2g/L 的样本，统计学差异得到了确认。
对于 PT 和抗凝血酶活性，两次测定之间的平均百分比差异低于个体内生物学变异，并且可以将 Fraser 的一个质量规范视为既无分析意义也无临床意义的混杂“噪声”因素。如果仪器在第一次运行时确定了结果，则对于 PT、APTT、D-二聚体浓度和抗凝血酶活性测试，不需要进行两次血浆高速离心。只有在纤维蛋白原>2g/L 或仪器无法在第一次运行时确定结果时，才需要进行该操作。
