Standardization and evaluation of the performance of the thrombin generation test under hypo- and hypercoagulability...

In order to standardize a thrombin generation() protocol, we analyzed the analytical variables and sensitivity of this test to hypo/hypercoagulability states.

The effect of the tissue factor concentration and the intra- and interassay precision were analyzed. To evaluate the hypercoagulability status, the plasma of women under an oral contraceptive was tested, while plasma from hemophilia A patients at 1, 3 and 7 days after recombinant FVIII infusion, and lyophilized plasma deficient in FVII or FVIII were used for the evaluation of hypocoagulability.

The intra-assay coefficient of variation was <10% with 1 and 5pM of low and high TF. The oral contraceptive users showed increased thrombin generation in comparison to non-users, which was more pronounced with low TF (endogenous thrombin potential ETP) p=0.0009; peak p=0.0009; lagtime p=0.0008). In relation to the FVIII-deficient plasma, a higher TG was observed as FVIII levels were increased and a better discrimination was obtained for different concentrations of FVIII with low TF (ETP p<0.0001; peak p<0.0001; lagtime p=0.0004). Using low TF, plasma from hemophilia A patients showed higher TG values after 1 day of recombinant FVIII infusion vs after 3 days (ETP p<0.0001; peak p<0.0001; lagtime p=0.0407), while the lowest values were observed after 7 days. With FVII-deficient plasma, thrombin generation was lower than normal plasma and a more pronounced difference was observed with high TF compared to low TF (ETP p<0.0001; peak p<0.0001; lagtime p<0.0001).

Under our conditions the thrombin generation test seems to be sensitive to evaluation of hyper/hypocoagulability states. Standardization of the thrombin generation test may have an application in the evaluation of bleeding and thrombotic disorders.