Summary

In haemophilia patients, a relationship is usually observed betweenthe clinical expression of the disease and plasmatic factorVIII/factor IX (FVIII/FIX) activity.However,it is known from clinicalexperience, that some haemophilia patients, despite similarFVIII/FIX plasma levels, could exhibit different bleeding phenotype.After determining preanalytical test conditions, we evaluatedthe thrombin generation capacity from haemophilia plasmasamples in various conditions and the potential usefulness ofthrombin generation test (TGT) in haemophilia patients. In aseries of 46 haemophilia patients (34 haemophilia A and 12 haemophiliaB patients), we found a significant correlation betweenplasmatic FVIII/FIX levels and endogenous thrombin potential (ETP), peak and time to peak obtained by thrombin generationmeasurement. In addition, a correlation was found between severeclinical bleeding phenotype and ETP. Our results suggestthat TGT could be a promising tool to evaluate haemostasis capacityin patients with haemophilia. Our ex vivo results, obtained24 hours after FVIII concentrate administration, showed that inpatients presenting similar plasmatic FVIIII levels, thrombin generationcapacity may be significantly different.These results suggestthat in patients with haemophilia,TGT could be useful forindividually tailoring prophylactic regimens as well as for adaptingclotting factors infusions in surgical situations, in addition toFVIII/FIX plasma clotting activities.