Thalassemias are a heterogeneous group of autosomal recessively inherited anemias of various degrees of severity. In thalassemia, the genetic defect results in reduced rate of synthesis of one of the globin chains that make up hemoglobin and is classified according to which chain of the hemoglobin molecule is affected. Hemoglobin B gene mutations result in β-thalassemia with reduced production of β-chain leading to the formation of abnormal heterotetramers, which bind to and damage erythrocyte membranes. Growth failure is one of the most common complications in thalassemia major. The child with thalassemia has a particular growth pattern, which is relatively normal until the age of 9-10 years and then deteriorates with a reduced or absent pubertal growth spurt resulting in final height shorter than the target one. The pathogenesis of growth failure in patients with thalassemia is mainly because of chronic anemia, iron overload, desferrioxamine toxicity, impaired GHRH-GH-IGF axis, and delayed puberty. Chronic anemia, if stays untreated, causes permanent bone malformations. Pituitary iron deposition leads to hormonal secretion abnormalities including impaired growth hormone secretion and delayed or absence of gonadotropin secretion. Desferrioxamine, the most commonly used chelating agent, is effective in diminishing iron, although it is found to have toxic effects on bones, which contribute to growth failure. In the case of desferrioxamine toxicity, alternative chelation agents can be used. Children, who undergo bone marrow transplant, often do not reach their target height, as they show variable growth during puberty and demonstrate poor spinal growth. Close follow-up and proper management is crucial for every patient to avoid thalassemia complications including the early manifestation of growth failure. Regular blood transfusions to maintain the hemoglobin level above 9 g/dl and appropriate chelation therapy to avoid the consequences of iron overload is the fundamental tool in the management of children with thalassemia. Therapeutic attempts with recombinant growth hormone have been performed in growth-retarded patients, showing, in the majority, an increase in growth response during the first year of treatment. In addition to growth hormone treatment, induction into puberty at a proper age using sex steroids is necessary in order to attain normal growth spurt and sexual maturity.
|Title of host publication||Handbook of Growth and Growth Monitoring in Health and Disease|
|Publisher||Springer New York|
|Number of pages||17|
|Publication status||Published - 1 Jan 2012|