Background: The mechanisms responsible for the increased thrombotic risk associated with thalassemia are still unclear. They might be related to the effects of red blood cell or endothelial cell derangements, increased numbers of platelets as well as abnormal plasma coagulation. Design and Methods: To evaluate the relative role played by cells and plasma we investigated 169 patients with thalassemia by means of thromboelastometry and thrombin generation tests. Thromboelastometry measures indices of the viscoelastic properties of whole blood after activation of coagulation and is characterized by the clotting time, which may be considered as a conventional coagulation time, clot formation time, defined as the time needed for the clot to reach a fixed firmness, and the maximum clot firmness, defined as the maximal amplitude of the tracing. Results: All the thromboelastometry parameters determined in whole blood (including shortened clotting time and clot formation time, and increased maximum clot firmness), were consistent with hypercoagulability, especially in splenectomized patients. Conversely, thrombin generation as determined in platelet-poor plasma was not. Conclusions: These findings point to blood cells and/or platelets rather than to plasma abnormalities as the most important determinants of the thrombotic risk observed in thalassemic patients who had been splenectomized. These results might have important diagnostic and therapeutic implications.
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