الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Thalassemia is the most common hereditary hemoglobinopathy, and occurs in 4.4/10,000 live births. In the developing world, the majority of patients die before the age of 20 years. Occurs due to absent or reduced synthesis of the β-globin chain results in ineffective erythropoiesis, peripheral hemolysis and hemolytic anemia. Thalassemia is treated with lifelong red blood cell transfusions associated with chelation therapy in order to limit chronic complications and premature deaths related to iron overload. This conventional therapy has dramatically improved survival and quality of life of patients. When thalassemia major patients receive regular blood transfusion, iron overload is inevitable because the human body lacks a mechanism to excrete excess iron. Iron accumulation is toxic to many tissues, causing heart failure, cirrhosis, liver cancer, growth retardation and multiple endocrine abnormalities. Bone disease is a very common complication in patients with thalassemia. Several studies have demonstrated that multiple factors contribute in the bone disease of the thalassemia major (TM) patients. Factors include multiple endocrine risk factors such as hypogonadism, hypothyroidism, growth hormone deficiency hypoparathyroidism, bone marrow expansion, hemosiderosis (iron overload), poor absorption of calcium, and the secondary chronic renal disease with low vitamin D Patients with thalassemia display low level of 25 hydroxyvitamin D; this is due to defective skin synthesis associated with jaundice might be implicated. Moreover, reduced physical activity due to the anemia and consequently lower sun exposure might contribute, while, in patients with severe liver disease, reduced 25-hydroxylase activity may also play a part. Despite remarkable improvements in medical care for patients with β- thalassemia, there is still only one definitive treatment option: allogeneic hematopoietic stem cell (HSC) transplantation, it is the only curative treatment in clinical practice. HSCT has been successfully performed over the last 30 years with current thalassemia-free survival rates of 80-90% in children transplanted with HLA-matched sibling donor (MSD) before the onset of complications related to their disease or to the supportive treatment. Hematopoietic stem cell transplantation potentially results in a better long-term quality of life than that observed in patients treated with regular transfusion and chelation therapy. Rapid bone loss during the first 6 months after transplantation (5.7% at the lumbar spine and 6.9% to 8.7% at the femoral neck sites) with no further decline between months 6 and 12, and recovery of bone mass during further follow-up. Several factors, mainly related to the immune system, affect outcomes of HSCT. The major obstacle to successful bone marrow transplantation (BMT) is graft-versus-host disease (GVHD). Vitamin D analogs have shown their efficacy in solid organ transplantation. The role of vitamin D and its effect on posttransplant outcomes has been evaluated in several studies that have mostly focused on bone loss, although more recently studies have investigated its role in immune modulation and graft-versus-host disease (GVHD) Dexa scan is A procedure that measures the amount of calcium and other minerals in a bone by passing x-rays with two different energy levels through the bone. A dual energy x-ray absorptiometry shows the strength and thickness of a bone and is usually done in the lower spine, hip, lower arm, wrist, fingers, and heel. It is used to diagnose osteoporosis (a condition of lower bone density), to see how well osteoporosis treatments are working, and to predict how likely the bones are to break. A dual energy x-ray absorptiometry also measures fat and muscle composition in specific parts of the body, such as the arms, legs, and pelvis. Consequently; DXA is considered the method of choice to assess bone status in thalassemia The aim of this study is to evaluate the Bone Density, Bone Architecture and Body Composition in children diagnosed with B Thalassemia major after allogenic hematopoietic stem cell transplantation, compared with other non-transplanted transfusion dependent B Thalassemic children. This study is a case control study that carried out on 3 groups of children each group consists of 20 patients aging from 5 to 14 years; first group include patients of thalassemia after HSCT in Bone marrow transplantation unit of Tanta university hospital and had completed nine months‘ post transplantation, second group include patients with thalassemia with regular blood transfusion, third group is a control group. Routine laboratory investigations including CBC, serum ferritin, electrolytes and assessment of bone density and bone architecture by: serum ionized ca, PTH, alkaline phosphatase, 25OH Vit D, DEXA scan Our study showed a statistically significant higher serum ca in group I&III as compared to group II, a statistically significant lower serum PTH in group II as compared to group I&III, and the serum ferritin was statistically significant higher in group II as compared to group I&III, a statistically significant higher serum alkaline phosphatase in group II as compared to group I. And a statistically significant lower serum vit D in group II as compared to group I&III, while the Z score by DEXA scan was significantly lower in group I & II as compared to group III. And there was statistically significant decrease in weight, BMI, fat mass in group II as compared to group I&III. There were positive correlations between Duration of HSCT & VIT D in group I, so as duration of HSCT increased the level of vit. D increased. The age of studied patients, serum creatinine level & serum ferritin level in group II were inversely related to vit D level. There were significant correlations between Weight, Height, Ms mass, Bone mass, FFM, TBW & No of transfusion and VIT D in group II.