A Whole Blood Thrombin Generation Assay to Assess Hyperc

个体患者静脉血栓形成的可能性只能根据临床因素粗略估计。从理论上讲，检测高凝状态的全球实验室检查将有助于预测血栓形成，其方式与低凝状态的常规检查相同（例如，PT、aPTT）在预测出血中的作用。为了尝试产生这样的全球测定，我们已经开发了“全血凝血酶生成”测定。通过添加钙和组织因子来刺激新鲜全血的凝结。测定凝血子样品的凝血酶活性。测量的参数是凝血酶活性的最大浓度、达到峰值活性的时间和凝血酶活性x时间的积分。我们测试了红细胞压积、白色细胞计数和血小板计数对这些参数的影响，发现所有细胞类型都会影响凝血酶的生成。我们还发现，每种凝血因子和天然抑制剂的浓度也影响测定系统中凝血酶的产生。该测试目前正应用于一组接受大手术的晚期恶性肿瘤患者。到目前为止，已有8名患者接受了研究。凝血酶生成在术前和术后有明显变化。我们还开始使用这种检测方法来评估镰状细胞病患者的高凝状态，并计划在脑癌患者中进行测试，这些患者也有很高的静脉血栓形成率，以确定结果是否能预测临床事件。

The likelihood of venous thrombosis in individual patients can be only roughly estimated on the basis of clinical factors. Theoretically, global laboratory tests that detect hypercoagulability would be helpful in predicting thrombosis in the same way that routine tests for hypocoagulability (eg., PT, aPTT) are in predicting bleeding. In an attempt to produce such a global assay we have developed a "whole blood thrombin generation" assay. Clotting of fresh whole blood is stimulated by adding calcium and tissue factor. Subsamples of the clotting blood are assayed for thrombin activity. The measured parameters are the maximal concentration of thrombin activity, the time to peak activity, and the integral of thrombin activity x time. We have tested the effect of hematocrit, white cell count, and platelet count on these parameters and have found that all of the cell types influence thrombin generation. We have also found that the concentration of each coagulation factor and natural inhibitor also affects thrombin generation in the assay system. The test is now being applied in a group of patients with advanced malignancies who undergo major surgery. So far 8 patients have been studied. There are obvious changes in thrombin generation between the pre-operative and post-operative days. We have also begun to use this assay in assessing hypercoagulability in patients with sickle cell disease and plan to test it in patients with brain cancer, who also have a very high rate of venous thrombosis, to determine whether the results will be predictive of clinical events.