Transferrin saturation >50% is suggestive of a high iron load. Transferrin saturation: Transferrin saturation is a surrogate marker for NTBI. LIC could also monitored by the use of superconducting quantum interference device (SQUID). Liver iron concentration (LIC) could be estimated by liver biopsy or T2* MRI, which provides a noninvasive alternative to liver biopsy. However, an assessment using serum ferritin levels may underestimate the iron concentration in the liver. Serum iron and ferritin: Serum iron level and ferritin levels are elevated. These free iron species generate reactive oxygen species with eventual tissue damage, organ dysfunction, and death ( Figure 1). įree iron species, such as labile plasma iron as well as labile iron pool in the RBCs accumulate when transferrin saturation exceeds 70%. ![]() This is combined with increased iron from the breakdown of RBCs and the increased iron introduced into the circulation by the transfusions necessary to treat thalassemia, plus inadequate excretory pathways lead to progressive deposition of iron in tissues and hemosiderosis occurs. Severe IE, chronic anemia, and hypoxia also cause increased gastrointestinal (GI) tract iron absorption. High levels of iron, closely associated with denatured hemoglobin, have been found in the membrane of β-thalassemic red cells. Marrow expansion also results in characteristic deformities of the skull and face, as well as osteopenia. Increased erythropoietin synthesis may stimulate the formation of extramedullary erythropoietic tissue, primarily in the thorax and paraspinal region. Anemia may produce cardiac enlargement and sometimes severe cardiac failure. The first response to anemia is an increased production of erythropoietin, causing a marked erythroid hyperplasia, which may range between 25 and 30 times normal. The ineffective erythropoiesis (IE) and anemia have several consequences producing the clinical picture of the disease. Apoptosis could contribute significantly to ineffective erythropoiesis and occurs primarily at the polychromatophilic erythroblast stage. Īlterations of erythroid precursors result in an enhanced rate of apoptosis, which is a programmed cell death. Also excess α-chain precipitation in the red cell membrane causes structural and functional alterations with changes in deformability, stability, and red cell hydration. The excess α-chains may, in minor amounts, combine with residual β- (in β+ -thalassemia) and γ-chains (whose synthesis persists usually in small quantity after birth), undergo proteolysis, or in large part become associated with the erythroid precursors with deleterious effects on erythroid maturation and survival. ![]() Unlike the deletions that constitute most of the α-thalassemia syndromes, β-thalassemias are caused by hundreds of mutations that affect all aspects of β-globin production: transcription, translation, and the stability of the β-globin product. The β-globin gene maps in the short arm of chromosome 11, in a region that contains also the delta globin gene, the embryonic epsilon gene, the fetal gamma genes, and a pseudogene (ψB1). The severity of β-thalassemia relates to the degree of imbalance between the α- and non-α-globin chains. The β-thalassemia syndromes are much more diverse than the α-thalassemia syndromes due to the diversity of the mutations that produce the defects in the β-globin gene. β-Thalassemia includes three main forms: Thalassemia Major, variably referred to as “Cooley’s Anemia” and “Mediterranean Anemia,” Thalassemia Intermedia, and Thalassemia Minor also called “β-thalassemia carrier,” “ β-thalassemia trait,” or “heterozygous β-thalassemia”. Β-Thalassemia syndromes are a group of hereditary blood disorders characterized by reduced or absent β-globin chain synthesis, resulting in reduced Hb in red blood cells (RBCs), decreased RBC production, and anemia.
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