Résumé
Regular blood transfusion in thalassemia can result in excessive damage to erythrocytes and tissues by generating free radicals and exhibiting oxidative stress. This stress is combated by a compensatory increase in antioxidative enzyme activity as of superoxide dismutase [SOD] and glutathione peroxidase [GPx], which reflects the depletion of antioxidants combating the oxidative stress induced by iron overload and balancing the redox state. This study aimed at correlating this enzymatic activity to the frequency of blood transfusion in beta-thalassemic children. Intervention: twenty-five beta-thalassemia major and 10 thalassemia intermedia children, ranging from two to eighteen years were sampled for serum iron, serum ferritin, and SOD and GPx activity. Values obtained were compared concerning transfusion frequency, chelation therapy in thalassemia major and intermedia cases. Showed abnormal high serum levels of iron in 80% of the studied population. Serum ferritin showed abnormal high levels in 93% and SOD and GPx activity was increased in all studied children. Serum iron, serum ferritin, SOD and GPx activity were significantly higher in thalassemia major than intermedia and higher in regular transfusing than irregular transfusing children and in irregular chelating children than in regular chelating children [p<0.05]. The highest values for serum iron, serum ferritin and SOD and GPx activity in all groups were obtained in thalassemia major cases, regular transfusing and irregular chelating. The least values were obtained for thalssemia intermedia cases, irregular transfusing and regular chelating. Differences between regular and irregular transfusing cases was greater and of statistically higher significance [p<0.01] than differences between regular and irregular chelating cases [p<0.05]. Thalassemia intermedia children who were irregular chelating, showed values of serum iron, serum ferritin and SOD and GPx activity as high as those in thalassemia major cases and showed normal levels with regular chelation therapy. With regular or irregular chelation, SOD and GPx activity was increasing with increased frequency of transfusion and was positively correlated to it [r=0.494], [p<0.01]. That regular chelation therapy is mandatory along with chronic transfusion therapy mildering the burden of iron overload associated with chronic transfusion responsible for oxidative damage. This should be applied especially in thalassemia major patients who transfuse at intervals of 4 weeks or less and intermedia patients, which inspite of infrequent transfusion load iron by gut absorption mainly responsible for the redox imbalance in thalassemia intermedia