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3 Haematology > Macrocytosis and Macrocytic Anaemia > Flashcards

Macrocytosis and Macrocytic Anaemia Flashcards

1
Q

cytosis means…

A

an increase in numbers

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2
Q

macrocytic anaemia has what MCV, RBC and Hb level?

A

low Hb
high MCV
low RBC

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3
Q

macrocytosis has what MCV, RBC and Hb level?

A

high MCV
normal Hb
normal RBC

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4
Q

MCV over ___ is macrocytic

A

100fl

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5
Q

how can you tell whether a cell is macrocytic or not?

A

compare it to the nucleus of a lymphocyte on blood film

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6
Q

name the 2 TRUE causes of macrocytosis

A

megaloblastic

non-megaloblastic

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7
Q

red cell precursors tend to have a nucleus T or F

A

T, only exception is reticulocytes

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8
Q

when do precursor cells get Hb?

A

start to get Hb as a precursor
reduce in size
lose nucleus once Hb content optimal

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9
Q

when do red cells lose their nucleus?

A

when Hb content in the cell is optimal

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10
Q

how long is the life span of a reticulocyte before it becomes a red cell?

A

7 days

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11
Q

what is a megaloblast?

A

an abnormally large nucleated red cell precursor with an immature nucleus

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12
Q

cause of megaloblastic anaemias?

A

defects in DNA synthesis and nuclear maturation

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13
Q

what cell functions are preserved in megaloblastic anaemias?

A

RNA and Hb synthesis

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14
Q

what red cell precursors undergo apoptosis in megaloblastic anaemia?

A

erythroblasts

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15
Q

why is a megaloblast big?

A

cytoplasmic development and Hb occur as normal despite cellular defects so it fails to become smaller

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16
Q

why is there anaemia in megaloblastic anaemia?

A

lack of mature red cells from the presence of macrocytes induces erythropoetin to stimulate precursor cells to form again, but these undergo apoptosis so the total RBC level is low

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17
Q

causes of megaloblastic anaemia

A

B12 deficiency
folate deficiency
drugs
genetics

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18
Q

why are B12 and folate causes of MA?

A

essential cofactors for nuclear maturation by enabling reactions for DNA synthesis and gene activity

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19
Q

what process facilitates the switching on and off of genes?

A

methylation of DNA

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20
Q

folate cycle is important for what processes? what conversion in this cycle is most important?

A

nucleoside synthesis

uridine to thymidine

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21
Q

methionine cycle is important for?

A

produces a methyl donor group that helps with DNA methylation (switching on/off of genes)

22
Q

what conversion interlinks the B12 and folate cycles? what relevance does this have?

A

homocysteine to methionine (B12 cycle needs a substance from the folate cycle to facilitate this)

if one system has a problem the other will too

23
Q

what protein is released from the stomach when th

A

R binder protein

24
Q

what happens to B12 in the GI tract? name the substances it binds to.

A
  • B12 freed from food by stomach acid
  • B12 binds to R binding protein
  • intrinsic factor released from gastric parietal cells and travels along with B12 to duodenum
  • pancreatic enzymes change pH of duodenum which frees B12 from RBP
  • these combine and travel the length of the gut to be absorbed at the ileum
25
Q

B12 is mainly in what foods?

A

meat/eggs

26
Q

causes of B12 deficiency

A 
vegan diet
PPIs
pernicious anaemia
atrophic gastritis
chronic pancreatitis
malabsorption eg crohns
excess utilisation eg haemolysis/pregnancy/malignancy
anticonvulsants
27
Q

define pernicious anaemia

A

autoimmune condition with destruction of gastric parietal cells resulting in B12 deficiency

28
Q

Hx of hypothyroidism, vitiligo, atrophic gastritis with B12 deficiency..

A

pernicious anaemia

29
Q

personal Hx of what conditions are associated with pernicious anaemia?

A

atrophic gastritis

autoimmune conditions eg hypothyroid, vitiligo, addisons

30
Q

folic acid is absorbed where?

A

jejeunum

31
Q

dietary folate is converted to what?

A

monoglutamate

32
Q

food sources of folate?

A

liver
leafy veg
fortified cereal

33
Q

B12 is absorbed in the ..

A

ileum

34
Q

daily requirement of B12

A

1.5ug

35
Q

daily requirement of folate

A

200ug

36
Q

clinical features of B12/folate deficiency

A 
anaemia signs
weight loss
diarrhoea
infertility
sore tongue
jaundice
developmental problems
37
Q

what clinical feature is specific to B12 deficiency

A

neuro problems esp degeneration of spinal cord and DC abnormalities

38
Q

B12/folate deficient patients get a __cytic anaemia

A

macro

39
Q

pancytopaenia means…

A

all cells low

40
Q

blood film of B12/folate deficiency

A

macrovalocytes (oval shaped macrocytes) and hypersegmented neutrophils

41
Q

Ix B12/folate deficiency

A

FBC
blood film
assay B12/folate levels in serum - CAREFUL for false positives/negatives
autoantibodies

42
Q

what autoantibodies are best for investigating B12/folate deficiency?

A

anti gastric parietal cell anaemia

anti-intrinsic factor

43
Q

Tx megaloblastic anaemia

A

B12 (IM) and folate (PO) supplementation

transfuse red cells ONLY if life threatening

44
Q

route of delivery of B12 supplement?

A

IM

45
Q

non megaloblastic causes of macrocytic anaemia? what do they affect?

A

alcohol
liver disease
hypothyroidism
- affect membrane of the red cell, not nuclear maturation
marrow failure eg myeloma/myelodysplasia/aplastic anaemia

46
Q

volume of the mature red cell is __ but the MCV is __ in non-megaloblastic macrocytosis

A

normal

high

47
Q

causes of NMMA?

A

increase in reticulocytes in response to blood loss/haemolysis
cold-agglutinins cause red cells to clump

48
Q

why can patients with pernicious anaemia appear jaundiced?

A

intramedullary haemolysis due to macrocytes dying in the marrow from being too big to get out of the capillaries
then converted to bilirubin

49
Q

proximal bowel removal will cause __cytic anaemia; why is this?

A

microcytic

iron is absorbed in proximal gut

50
Q

distal bowel removal will cause ___cytic anaemia; why is this?

A

macrocytic

B12 is absorbed in the distal gut

3 Haematology (30 decks)

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