RESUMEN
A group of 40 thalassaemic patients [20 splenectomized and 20 nonsplenectomized] from the Haematology Unit of Tanta University Hospital [age range: 3-14 years] were studied to identify the mechanisms by which haemorrhagic and thrombotic complications occur in thalassaemic patients. The patients' levels of protein C, antithrombin III and in vitro platelet aggregation in response to collagen were compared with those of 20 controls. The study suggests that thrombocytosis, increased platelet aggregation and decreased natural coagulation inhibitors [protein C and antithrombin III] in splenectomized thalassaemic children may be significant in thrombotic complications in such patients. Defective platelet aggregation and prothrombin activity in nonsplenectomized children may also give rise to haemorrhagic tendencies