Haemostasis Research Unit, Department of Haematology, University College London, London, UK.
Int J Lab Hematol. 2013 Dec;35(6):652-7. doi: 10.1111/ijlh.12109. Epub 2013 May 30.
The Clinical and Laboratory Standards Institute (CLSI) has produced a guideline detailing how to determine the activated partial thromboplastin time's (APTT) sensitivity to clotting factor deficiencies, by mixing normal and deficient plasmas. Using the guideline, we determined the factor sensitivity of two APTT reagents.
APTTs were performed using Actin FS and Actin FSL on a Sysmex CS-5100 analyser. The quality of factor-deficient and reference plasmas from three commercial sources was assessed by assaying each of the clotting factors within the plasmas and by performing thrombin generation tests (TGT).
Testing samples from 50 normal healthy subjects gave a two-standard deviation range of 21.8-29.2 s for Actin FS and 23.5-29.3 s for Actin FSL. The upper limits of these ranges were subsequently used to determine APTT factor sensitivity. Assay of factor levels within the deficient plasmas demonstrated that they were specifically deficient in a single factor, with most other factors in the range 50-150 iu/dL (Technoclone factor VII-deficient plasma has 26 iu/dL factor IX). APTTs performed on mixtures of normal and deficient plasmas gave diverse sensitivity to factor deficiencies dependent on the sources of deficient plasma. TGT studies on the deficient plasmas revealed that the potential to generate thrombin was not solely associated with the levels of their component clotting factors.
Determination of APTT factor sensitivity in accordance with the CLSI guideline can give inconsistent and misleading results.
临床和实验室标准协会（CLSI）已经制定了一个指南，详细说明了如何通过混合正常和缺乏的血浆来确定激活部分凝血活酶时间（APTT）对凝血因子缺乏的敏感性。我们使用该指南确定了两种 APTT 试剂的因子敏感性。
使用 Actin FS 和 Actin FSL 在 Sysmex CS-5100 分析仪上进行 APTT。通过测定血浆中每种凝血因子并进行凝血酶生成试验（TGT）来评估来自三个商业来源的缺陷和参考血浆的因子质量。
对 50 名正常健康受试者的样本进行测试，得到 Actin FS 的 2 个标准差范围为 21.8-29.2 秒，Actin FSL 的 23.5-29.3 秒。随后使用这些范围的上限来确定 APTT 因子敏感性。对缺陷血浆中因子水平的测定表明，它们仅在单个因子中缺乏，大多数其他因子在 50-150 iu/dL 范围内（Technoclone 因子 VII 缺乏的血浆有 26 iu/dL 因子 IX）。对正常和缺陷血浆混合物进行的 APTT 表现出对因子缺乏的不同敏感性，这取决于缺陷血浆的来源。对缺陷血浆的 TGT 研究表明，生成凝血酶的潜力不仅仅与它们的成分凝血因子的水平相关。
根据 CLSI 指南确定 APTT 因子敏感性可能会产生不一致和误导性的结果。
