maacrocytosis and microcytic anaemia Flashcards
what is microcytic anaemia?
anaemia in which the red cells have a larger than normal volume
what is macrocytic anaemia?
anaemia in which the red cells have a larger than normal volume
what is the unit to measure MCV?
femtolitres (1 femtoliter is equal to 10^-15L)
how to measure MCV?
Modern analysers use the light scatter properties of red cells to measure the MCV.
normal size of the red cell is the same size as the
nucleus of the lymphocyte
what are the two causes of macrocytosis?
genuine (true) or spurious (false)
what are the two causes of true macrocytosis?
megaloblastic
non-megaloblastic
normal precurors of red cells excluding the reticulocyte are?
erythroblasts or normoblasts and have a nucleus (they are the same)
where are normal red cells precursors based?
marrow-based
what is the immediate precursor of the red blood cell?
reticulocyte (loses of nucleus) and have a small amount of RNA which is lost after about 24 hours
reticulocytes leave marrow to join
circulation
developing erythroblasts?
accumulate Hb
reduce in size and increasing nuclear maturation
stop dividing and lose nucleus
what triggers loss of nucleus and end of division?
critical Hb content
at the point the nucleus is lost and the division ends?
the erythroblast becomes a reticulocyte
between pronormoblaast and late normoblast cells are?
increasing in HB, becoming smaller still has nucleus
what is an megaloblast?
an abnormally large nucleated red cell precursor with an immature nucleus and more open chromatin and have a larger nucleus
what are the characteristics of megaloblastic anaemias?
lack of red cells due to predominant defects in DNA synthesis and nucleus maturation but RNA and hemoglobin synthesis are preserved
pro erythroblasts ——– but in ——— erythroblasts, division is ——- and apoptosis ———-
expand, reduced
increased
in a megaloblast what occurs normally?
cytoplasmic development and haemoglobin accumulation
megaloblasts are
precursors that are bigger with an immature nucleus
once the hemoglobin level in the cell is optimal the nucleus if extruded leaving behind ?
a bigger than normal red cell ie. microcyte
but overall in megaloblastic anaemia there are?
fewer macrocytes and hence anaemia
the end result after enucleation you go from megaloblast to
macrocyte
megaloblastic anaemia is?
charaacteristed by larger precursor cells with an immature nucleus leading to microcytic anaemia
what are the causes of megaloblastic anaemia?
B12 deficiency
folate deficiency
others such as drugs and rare inherited abnormalities
why are B12 and folate essential co-factors?
they are co-factors in linked biochemical reaction regulating
what are the functions of B12 and folate?
DNA synthesis and nuclear maturation - (e.g. blood cell effect)
DNA modification and gene activity – (e.g. nervous system)
B12 is rich in which foods?
meat and meat products, eggs
what is pernicious anaemia?
autoimmune condition with resulting destruction of gastric parietal cells
gastric parietal cells produce?
Intrinsic factor
with someone who have pernicious anaemia?
there is resulted in intrinsic factor deficiency with N12 malabsorption and deficiency
what conditions are associated with pernicious anaemia?
associated with atrophic gastritis and personal or family history of other autoimmune disorders (eg. hypothyroidism, vitiligo, Addison’s disease)
where is folate absorbed?
in jejunum via duff ion and active transport
dietary floats are converted to?
mono glutamate
folate deficiency can show up in?
4 months
what is the daily dietary intake of folate?
200ug/day
what is the daily requirement of B12?
1.5ug/day
what are the causes of folate deficiency?
inadequate intake
malabsorption
excess utilisation
drugs
what are examples of excesss utilization of folate?
hemolysis
exfoliating dermatitis
pregnancy
malignancy
what are the clinical features of B12/folate deficiency?
symptoms/signs of anaemia
weightless, diarrhea, infertility
sore tongue, jaundice
developmental problems
B12 deficiency causes
neurological problems - posterior/dorsal column abnormalities, neuropathy, dementia, psychiatric manifestations
what is the laboratory diagnosis of B12.folate deficiency?
microcytic anaemia (red cell count is low) pancytopenia (all cells low) in some patients
assay B12 and folate levels in serum has a flaws such as?
: low levels may not indicate deficiency and normal levels may not indicate normalcy!
check for autoantibodies?
(anti-intrinsic factor (IF) & anti gastric-parietal cell (GPC)
what are the flaws of checking for auto-antibodies?
: anti-GPC sensitive, not specific; anti-IF: more specific, not sensitive)
shilling’s test
not routinely used anymore
bone marrow examination
not required usually
treatment of megaloblastic anaemia?
treat cause where possible
folic acid tablets (5mg per day)
in pernacious anaemia?
vitamin B12 (tydroxycobalamin) injections for life
only if potentially life-threatening anaemia?
transfuse red cells
in the absence of anaemia maacrocytosis
is due to alcohol, liver disease, hypothyroidism
what are the marrow failure causes?
myelodysplasia
myeloma
aplastic anaemia
spurious macrocytotsis?
the volume of the mature red cell is normal but the MCV is measured as high
retiulocytosis?
An increase in reticulocyte numbers occurs as a marrow response to acute blood loss or red cell breakdown (haemolysis)
Reticulocytes are bigger than mature red cells and are analysed along with these for the MCV measurement.
what is cold-agglutinins disease?
these are proteins that are activated at room temperature these clumps of agglutinated red cells and are registered as 1 giant cell
upper limit of normal of mcv
is 105
upper limit of normal of mcv
is 105
patients with pernicious anaemia can be?
appear mildly jaundiced due to intramedullary hemolysis
what is intramedullary haemolysis?
Red cells die prematurely in the marrow
Haemoglobin and lactate dehydrogenase (LDH) are released from dead red cells
Haemoglobin converted to bilirubin
pancytopenia can complicate?
severe megaloblastic anaemia
