Macrocytosis and Anaemia Flashcards
Define macrocytosis
Macro = big Cytosis = an increase in cell numbers
What is macrocytic anaemia?
Red cells have a larger than normal volume
Which red cell indices express size?
MCV: Mean corpuscular volume
How is MCV measured?
Modern analysers meaure MCV using light scatter properties of red cells
How to recognise macorcytes on a blood film?
Regardless of circumstance, size of a lymphocyte will not change
Compare the size of red cell to nucleus of mature lymphocyte – should be smaller
Macrocytes will be larger than nucleus of lymphocyte
What are the 2 types of causes of macrocytosis?
Megaloblastic causes
Non-megaloblastic causes
Name the ENUCLEATED red cell precursor
Erythroblasts or normoblasts in the bone marrow
What is the immediate, enucleated precursor of RBC?
Reticulocyte (with RNA remnants which are lost in circulation over 24hrs)
List the events/stages in erythroblast maturation
- Accumulation of Hb
- Reduction in size and simultaneous nuclear maturation
- Enucleation when Hb concentration reaches a critical stage - BECOMES RETICULOCYTE
What is a megaloblast?
Abnormally large nucleated RBC precursor with an IMMATURE NUCLEUS
What are the specific characteristics of megaloblastic anaemias?
Lack of red cells
Predominant defect in DNA synthesis and maturation
Hb synthesis and RNA synthesis is preserved
Megaloblast vs macrocyte
Megaloblast is immature and nucleated, macrocyte is mature and enucleated
Causes oof megaloblastic anaemia
B12 deficiency Folate deficiency Others: Drugs Rare inherited abnormalities
Importance of B12 and Folate
B12 and folate are essential co-factors in linked biochemical reactions regulating:
a) DNA synthesis and nuclear maturation - (e.g. blood cell effect)
b) DNA modification and gene activity – (e.g. nervous system)
