Poller L, Houghton D, Carroll J
Department of Pathological Sciences, Medical School, University of Manchester, U.K.
Br J Haematol. 1994 Dec;88(4):866-73. doi: 10.1111/j.1365-2141.1994.tb05129.x.
The mean normal prothrombin time (MNPT) based on the fresh plasma of 20 healthy individuals is the recommended way to derive a normal value for the prothrombin ratio. This is generally believed to give a reasonable representation of the normal in the local population, but there may be difficulty in obtaining a good representative sample in some centres. The alternative of a uniform lyophilized 'normal' plasma has been suggested. The comparative value of a widely used commercial 'normal' plasma and the MNPT has been assessed in an international study at 37 centres. Two common thromboplastins were tested using the local coagulometer methods. The variability of the results and their relative performance in local thromboplastin calibration to derive the International Sensitivity Index (ISI) were assessed. The reliability of the two types of normal in local system ISI calibration with different lyophilized plasma calibrants has also been tested. When the lyophilized 'normal' was substituted for the MNPT in ISI determination no appreciable difference in the degree of correction for coagulometers effects on International Normalized Ratios was found.
基于20名健康个体新鲜血浆的平均正常凝血酶原时间（MNPT）是得出凝血酶原比值正常数值的推荐方法。一般认为这能合理代表当地人群的正常情况，但在一些中心获取具有良好代表性的样本可能存在困难。有人建议使用统一的冻干“正常”血浆作为替代。在一项由37个中心参与的国际研究中，对一种广泛使用的商业“正常”血浆与MNPT的比较价值进行了评估。使用当地凝血仪方法对两种常用的组织凝血活酶进行了检测。评估了结果的变异性及其在当地组织凝血活酶校准以得出国际敏感度指数（ISI）方面的相对性能。还测试了使用不同冻干血浆校准物在当地系统ISI校准中两种类型正常样本的可靠性。当在ISI测定中用冻干“正常”样本替代MNPT时，未发现凝血仪对国际标准化比值影响的校正程度有明显差异。
