Assiut University, Pediatrician Department

Beta Thalassemia major (TM) is a hereditary disease caused by defective Beta globin chain synthesis, resulting in abnormal as well as a decreased quantity of globin chains, ineffective erythropoiesis, haemolysis and increased red blood cell turnover (Cooley, etal, 1927). described the first patient with anemia, splenomegaly, cranial & facial bone enlargement. Pathophysiology of bone denisity changes in beta thalassemia major Several studies had been previously evaluated; shown that multiple factors may act in concert to produce bone disease in beta thalassemia major (TM) including bone marrow expansion (Shamshirsaz, etal, 2003). hypogonadism (Anapliotou,Saka&Jensen,1998), defective growth hormone-insulin-like growth factor-1 (GH-IGF-1) axis (Soliman,etal,1998), altered pattern of cytokines (Morabito,etal,2007), iron deposit in bone ((Bordat,etal,1993),deferoxamine bone toxicity (Chan ,etal, 2002),and vitamin D deficiency (Dandona, etal, 1987). Some of these pathogenic factors, directly and/or indirectly, affect osteoblastic population, leading to depressed bone formation, while others often increase osteoclastic bone resorption.

Complications of transfusion dependent poorly controlled beta thalassemia major are;(1)-Osteoprosis; Iron overload impairs osteoid maturation and inhibits local mineralization to form focal osteomalacia. In addition, integration of iron in calcium hydroxyapatite affects the growth of crystals, which causes mineralization failure (Chan, etal, 2002), defective growth hormone-insulin-like growth factor-1 (GH-IGF-1) axis (Soliman, etal, 1998),altered pattern of cytokines (Morabito,etal, 2007), iron deposit in bone (Bordat, etal, 1993), deferoxamine bone toxicity (Chan, etal,2002). and vitamin D deficiency (Dandona, etal, 1987). (2)-Fractures; The introduction of red blood cell transfusion and concomitant iron chelation therapy has led to improved bone health through various mechanisms. It leads to a reduction in medullary expansion and cortical bone thinning, the reduced incidence of hypogonadism, and a reduction in other endocrine complications such as hypoparathyroidism and metabolic disorders that predispose to low bone density and fractures( Multicentre study, italian working group 1995). Z-score of bone density will be calculated. Z score is the preferred parameter in children. which is calculated as the number of standard deviations above or below the mean for the patient's age, sex,