Perkins H A, Hymas P G
Am J Clin Pathol. 1979 Nov;72(5):855-7. doi: 10.1093/ajcp/72.5.855.
Definition of one unit of factor VIII procoagulant activity may be imprecise, for a number of reasons. Levels in individual normal plasmas differ sufficiently that small pools do not have equivalent activities. Large pools cannot be prepared without loss of activity because of the lability of factor VIII. Human factor VIII may not be stable at --20 C. Lyophilized standards may vary in activity because of difficulties in dissolving the materials. The authors have prepared standards that are stable at --20 C for years using beef plasma diluted in outdated human blood bank plasma. The level of activity of this working standard is verified by repeated assays of lyophilized national standards and of small pools of normal donor plasma. The standard is equally applicable to one- or two-stage assays for factor VIII.
由于多种原因，凝血因子VIII促凝血活性的一个单位的定义可能并不精确。个体正常血浆中的水平差异很大，以至于小样本池不具有等效活性。由于因子VIII的不稳定性，无法在不损失活性的情况下制备大样本池。人因子VIII在-20°C时可能不稳定。由于材料溶解困难，冻干标准品的活性可能会有所不同。作者使用稀释在过期人血库血浆中的牛肉血浆制备了多年来在-20°C稳定的标准品。通过对冻干国家标准品和正常供体血浆小样本池的重复测定来验证该工作标准品的活性水平。该标准同样适用于因子VIII的一步法或两步法检测。
