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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