الفهرس 
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Abstract
1<Beta-thalassemias are heterogeneous autosomal recessive hereditary anemias characterized by reduced or absent β globin chain synthesis. The resulting relative excess of unbound α globin chains precipitate in erythroid precursors in the bone marrow, leading to their premature death and, hence, to ineffective erythropoiesis. β-thalassemia phenotypes are variable ranging from the severe transfusion dependent thalassemia major to the mild form of thalassemia intermedia. Patients with the major form of the disease have severe microcytic and hypochromic anemia, hepatosplenomegaly, and usually come to medical attention within the first two years of life. Without treatment, affected children have severely compromised growth and development and shortened life expectancy. Therapy, aimed at reducing transfusional iron overload, allows for normal growth and development and extends life expectancy into the third to fifth decade (Borgna-Pignatti et al., 2004)
Therefore iron chelating agents are given to reduce this transfusional iron overload(Nancy, et al2000).
This study was designed to find out the effect of iron chelating agents on hearing sensitivity.
Also to correlate hearing sensitivity with duration of drug intake.age of patient, level of serum ferritin and haemoglobin level.
This was achieved by examining fifty Egyptian patients; 15 (30%) females and 35 (70%) males with transfusion dependent β-thalassemia and their ages ranged from5-18 years.
All patients recive regular blood transfusion and iron chelation therapy. Thirty sex(72% )patients recive Deferasirox,thirteen(26%) patients recive Deferipron and one patient(2%)recive Deferoxamaine
Each patient was subjected to full history taking, stress on transfusin history and iron chelation therapy,
Investigations( cbc ,serum iron and serum ferritin)
Otological examinations and audiological evaluation.
Audiological testes included pure tone audiometry otoacustic emissions and auditoy brainstem response.