Chapter 5 in Haemtology
(Macrocytic Anaemia) summary
-Macrocytic anaemia show an increased size of circulating red
cells (MCV>98 fl).Causes include vitamin B12 (B12,cobalamin) or folate
deficiency,alcohol,liver disease, hypothyroidism,myelodysplasia,
paraproteinneamia, and the neonatal period.
-B12 or folate deficiency cause megaloblastic anaemia, in which the bone marrow erythroblast have a typical abnormal appearance.
-B12 deficiency is usually
caused by B12 malabsorption brought about by pericious
anaemia in which there is autoimmune gastric, resulting in severe deficiency of
intrinsic factor, a glycoprotien made in stomach which faciliates B12
absorption by the ileum.
-Other gastrointestinal
diseases as well as a vegan diet may cause B 12 deficiency .
-folate deficiency may be caused by a poor diet ,malabsorption (e.g.gluten-induced
enteropathy)or excess cell turnover(e.g.pregnancy,haemolytic anaemias,
malignancy)
-Treatment of B 12 deficiency
is usually with injection of hydroxocobalamin and of
folate deificency with oral folic (pteroyglutamic) acid.
-Rare cause of megaloblastic
anaemia include inborne errors of B 12 or folate
transport oe metabolism , and defects of DNA synthese not related toB12 or
folate.
From
book: Essentail Haematology A.V.HOFFBRAND,P.A.H.MOSS.6EDITION
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