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Haematology summray 4


Chapter 4 in Heamtology (Iron overload) summary

-Iron overload is caused by excessive absorption of iron from food (genetic haemochromatosis ) or by repeated blood transfusions in patients with refractory anaemias. Each unit of blood contains 200-250 mg of iron.

-Excess iron aborbed from the gastrointestinal tract accumulates in the parenchymal cells of the liver, endocrine organs and, in sever cases, the heart.

-Transfusional iron overload causes damage to these organs and also iron accumulation in macrophages of the reticuloendothelial system.

 -Genetic haemochromatosis is usually caused by homozygous mutation (845G to A) of the gene causing a low serum hepcidin level. Rare forms exist caused by mutations of other genes coding for protiens ( hemojuvelin,hepcidin,transferrin receptor 2 ferroportin).Repeated venesections are used to reduce the body iron burden.

-Transfsional iron overload most frequently occurs in thalassaemia major but also in other transfusion dependent refractory anaemias (e.g.some cases of myelodysplasia , sickle cell anaemia, primary myelofibrosis,red cell aplasia and aplastic anaemia).

-Cardiac faliure or arrhythmia casued by cardiac siderosis, best detected by MRI, is the most frequent cause of death from trasnfusional iron overload.

-Treatment is with iron chelating drugs: deferoxamine (given subcutaneously or intravenously ), deferiprone or deferasirox (which are both active bu mouth). Combinationsa of chelators are also employed.
 

From book: Essentail Haematology A.V.HOFFBRAND,P.A.H.MOSS.6EDITION

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