Haemostasis Section, Biotherapeutics Group, National Institute for Biological Standards and Control (NIBSC), Potters Bar, Hertfordshire, United Kingdom.
Int J Lab Hematol. 2020 Dec;42(6):810-818. doi: 10.1111/ijlh.13277. Epub 2020 Jul 8.
Accurate measurement of coagulation factors is essential, especially for diagnosis of deficiency. Clinical laboratories use commercially available plasma calibrators, which should be traceable to the relevant plasma International Standard (IS). This study assessed the relationship between the plasma IS for factors IX (FIX) and VIII (FVIII) and some commonly used commercial calibrators. Calibrators from seven manufacturers were assayed for FIX and FVIII activity by one-stage clotting assay (OSCA) using different activated partial thromboplastin time (APTT) reagents and deficient plasmas, or chromogenic assay (CA). Results were calculated relative to the 4th IS Factors II,VII,IX,X, Plasma or the 6th IS Factor VIII/VWF, Plasma. Results for each calibrator were similar across the APTT reagents and deficient plasmas used. All calibrators showed a recovery of 90%-111% of the manufacturers' values, except calibrator C, which had recovery of around 85%. CA gave similar results, with good recovery for all but calibrator C. Similar low recoveries for OSCA and CA were found for a different lot of calibrator C and for a different calibrator product from manufacturer C. When all calibrators from manufacturer C were assayed by OSCA using the manufacturer's own deficient plasmas and APTT reagents, the mean recovery was still below 90%. Overall, there was good traceability of the international unit between the IS and commercial calibrator plasmas. Calibrators from one manufacturer consistently yielded lower than expected values for FIX and FVIII. This could lead to an over-estimation of the coagulation factor content in patient samples and demonstrates the importance of careful choice of calibrator.
准确测量凝血因子至关重要，尤其是在诊断缺乏症时。临床实验室使用市售的血浆校准品，这些校准品应可追溯至相关的血浆国际标准（IS）。本研究评估了凝血因子 IX（FIX）和 VIII（FVIII）的血浆 IS 与一些常用商业校准品之间的关系。使用不同的活化部分凝血活酶时间（APTT）试剂和缺乏的血浆，或发色底物法（CA），对来自七个制造商的校准品进行 FIX 和 FVIII 活性的测定。结果相对于第 4 个 IS 因子 II、VII、IX、X、血浆或第 6 个 IS 因子 VIII/VWF、血浆进行计算。使用的 APTT 试剂和缺乏的血浆中，每个校准品的结果相似。除校准品 C 外，所有校准品的回收率均为制造商值的 90%-111%，校准品 C 的回收率约为 85%。CA 也给出了相似的结果，除了校准品 C 之外，所有校准品的回收率均良好。对于不同批次的校准品 C 和来自制造商 C 的不同校准品产品，OSCA 和 CA 的回收率也较低。当使用制造商自己的缺乏血浆和 APTT 试剂对制造商 C 的所有校准品进行 OSCA 检测时，平均回收率仍低于 90%。总体而言，国际单位之间的国际标准和商业校准品血浆之间具有良好的可追溯性。一个制造商的校准品始终对 FIX 和 FVIII 产生低于预期的值。这可能导致对患者样本中凝血因子含量的高估，并证明了仔细选择校准品的重要性。
