Book contents
- Frontmatter
- Contents
- List of contributors
- Foreword
- Part I Introduction to hemochromatosis
- Part II Genetics of hemochromatosis
- Part III Metal absorption and metabolism in hemochromatosis
- Part IV Diagnostic techniques for iron overload
- Part V Complications of iron overload
- Part VI Therapy of hemochromatosis and iron overload
- Part VII Infections and immunity in hemochromatosis
- Part VIII Hemochromatosis heterozygotes
- Part IX Relationship of hemochromatosis to other disorders
- 42 Thalassemias and their interactions with hemochromatosis
- 43 Iron overload in sideroblastic and other nonthalassemic anemias
- 44 Hemochromatosis, iron overload, and porphyria cutanea tarda
- 45 Interactions of alcohol, iron and hemochromatosis
- 46 Iron overload in African Americans
- Part X Animal models of hemochromatosis and iron overload
- Part XI Screening for hemochromatosis
- Part XII Hemochromatosis: societal and ethical issues
- Part XIII Final issues
- Index
42 - Thalassemias and their interactions with hemochromatosis
from Part IX - Relationship of hemochromatosis to other disorders
Published online by Cambridge University Press: 05 August 2011
- Frontmatter
- Contents
- List of contributors
- Foreword
- Part I Introduction to hemochromatosis
- Part II Genetics of hemochromatosis
- Part III Metal absorption and metabolism in hemochromatosis
- Part IV Diagnostic techniques for iron overload
- Part V Complications of iron overload
- Part VI Therapy of hemochromatosis and iron overload
- Part VII Infections and immunity in hemochromatosis
- Part VIII Hemochromatosis heterozygotes
- Part IX Relationship of hemochromatosis to other disorders
- 42 Thalassemias and their interactions with hemochromatosis
- 43 Iron overload in sideroblastic and other nonthalassemic anemias
- 44 Hemochromatosis, iron overload, and porphyria cutanea tarda
- 45 Interactions of alcohol, iron and hemochromatosis
- 46 Iron overload in African Americans
- Part X Animal models of hemochromatosis and iron overload
- Part XI Screening for hemochromatosis
- Part XII Hemochromatosis: societal and ethical issues
- Part XIII Final issues
- Index
Summary
Thalassemia syndromes
Thalassemia syndromes are very frequent in some parts of the world, especially Mediterranean and Asiatic countries. When the genetic defect underlying these syndromes is severe, iron overload becomes one the major clinical problems and can be life-threatening.
Pathogenesis of iron overload
The pathogenesis of iron overload in patients with thalassemia is multifactorial. Iron overload can develop as a consequence of increased iron absorption from the gastrointestinal tract, similar to that which occurs in persons with hemochromatosis or transfusion-dependent anemias. Under normal conditions, iron homeostasis is maintained by modulation of absorption of dietary iron (the only way iron enters the body). This, in turn, is regulated by a balance between iron needed for the erythron (more than three-fourths of total body iron) and for storage. Thus, all conditions characterized by increased erythropoiesis or by a reduction of iron stores are accompanied by enhanced iron absorption. Moreover, patients who have anemia with increased but ineffective erythropoiesis are at greater risk of developing severe iron overload than patients with hemolytic anemias with increased and effective erythropoiesis, e.g., patients with hereditary spherocytosis, who rarely develop iron overload. In the presence of severe anemia, intestinal hypoxia also appears to increase iron absorption.
Anemia is very mild in β-thalassemia heterozygotes and in persons with α-thalassemia in whom two or three alpha globin genes are functioning, and associated iron overload is rare. In these patients, inefficient erythropoiesis is relatively mild.
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- Information
- HemochromatosisGenetics, Pathophysiology, Diagnosis and Treatment, pp. 435 - 441Publisher: Cambridge University PressPrint publication year: 2000
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