A chronic hypercoagulable state and life-long platelet activation in beta thalassemia major.

Increased frequency of thromboembolic events has been recently observed in patients with thalassemia major (TM), causing hypoxemia and cor pulmonale. Autopsy findings demonstrated "old" and recent pulmonary and renal infarcts as well as premature atherosclerosis. Studies to determine hypercoagulability showed: impaired platelet aggregation, increased circulating platelet aggregates, shortened platelet survival, enhanced excretion of urinary metabolites of thromboxane A2 (TXA2) and prostacyclin and decreased plasma levels of Protein C, Protein S or anti-thrombin III. Erythrocytes from TM patients enhanced thrombin formation in a "prothrombinase" assay (using a chromogenic substrate). Chronic anti-thrombotic therapy may be indicated in thalassemic patients to prevent the cardiac and pulmonary complications.