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