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Haematology > Macrocytosis and macrocytic anaemia > Flashcards

Macrocytosis and macrocytic anaemia Flashcards

1
Q

macrocytosis and macrocytic anaemia are the same thing, true or false

A

false

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2
Q

define macrocytic anaemia

A

anaemia with red cells being abnormally larger than normal (^MCV)

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3
Q

what are the units of MCV

A

femtolitres

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4
Q

in a blood film, what is used as reference for RBC size

A

the nucleus of a small, mature lymphocyte is used as a reference for RBC size as it is unchanging

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5
Q

what are the main causes of macrocytic anaemia

A

genuine / true

spurious / false

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6
Q

what are genuine causes of macrocytic anaemia

A

megaloblastic

non-megaloblastic

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7
Q

what accumulates in developing erythroblasts/normoblasts

A

Hb

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8
Q

what happens when Hb concentration has reached threshold

A

erythroblasts stop dividing and enucleation occurs to become a reticulocyte

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9
Q

define erythroblast

A

normal red cell precursor with a nucleus

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10
Q

define megaloblast

A

large red cell precursor with an immature nucleus - open chromatin seen

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11
Q

what is the main cause of megaloblastic anaemias

A

lack of red blood cells due to defects in DNA synthesis and nuclear maturation

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12
Q

RNA synthesis and Hb accumulation are preserved in megaloblasts, true or false

A

true

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13
Q

what happens in the lineage of megaloblasts

A

EPO causes expansion of primitive precursors

cell division reduces and apoptosis occurs resulting in fewer overall cells

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14
Q

what happens when Hb concentration threshold is reaches in a megaloblast

A

enucleation occurs which leaves behind a bigger than normal red cell ie macrocyte

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15
Q

what are causes of megaloblastic anaemia

A

B12 deficiency
folate deficiency
drugs
inherited conditions

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16
Q

what are B12 and folate and their functions

A

essential cofactors in biochemical reactions
blood cells - DNA synthesis and nuclear maturation
neuro - DNA modification and gene activity

17
Q

in which foods is B12 found

A

meat and meat products

18
Q

describe the absorption of B12 in the GI tract

A

acid in the stomach causes B12 to dissociate from meat and bind to haptocorrin
gastric parietal cells secrete IF
B12 and haptocorrin compound and IF travel to gut
pancreatic secretion increase pH and cause B12 to dissociate from haptocorrin and bind to IF
B12 and IF complex travel to distal gut and are internalised by cells with cubulin receptors in ileum

19
Q

what is pernicious anaemia

A

autoimmune condition attacking gastric parietal cells resulting in IF deficiency and B12 malabsorption and deficiency

20
Q

how is folate absorbed in the gut

A

converted to monoglutamine

and absorbed in jejunum

21
Q

how long do B12 stores last in the body

A

2-4 years

22
Q

how long do folate levels last in the body

A

4 months

23
Q

what are symptoms of B12 and folate deficiency

A

fatigue, SOB, pallor
weight loss, diarrhoea, infertility
sore tongue, jaundice
developmental delay

24
Q

symptoms of B12 deficiency alone

A 
neurological: 
neuropathy 
dementia 
psychiatric 
SCDC
25
Q

how can you diagnose megaloblastic anaemia in the lab

A 
macrocytic anaemia (low Hb, raised MCV)
pancytopaenia in some 
blood film = macrovalocytes + hypersegmented neutrophils
B12 + folate assays - not accurate 
antibodies: anti-IF, anti-GPC
26
Q

causes of B12 deficiency

A 
diet
atrophic gastritis 
pernicious anaemia 
gastrectomy 
SBBO 
coeliac 
crohns 
inherited deficiencies
27
Q

causes of folate deficiency

A 
diet 
alcoholics 
pregnancy 
malignancy 
malabsorption 
haemolysis 
anticonvulsants
28
Q

treatment of megaloblastic anaemia

A

treat cause
lifelong B12 injections
folic acid tablets 5mg PO OD
only transfuse if emergency

29
Q

causes of non-megaloblastic anaemia

A

red cell membrane changes

may or may not be associated with anaemia:

  • alcohol
  • liver disease
  • hypothyroidism

marrow failure - associated with anaemia

  • myelodysplasia
  • myeloma
  • aplastic anaemia
30
Q

what is spurious macrocytosis

A

normal RBC volume but MCV is high

31
Q

causes of spurious macrocytosis

A

reticulocytosis

cold agglutins

32
Q

why can patients with pernicious anaemia appear mildly jaundiced

A

due to intramedullary haemolysis

33
Q

what is ineffective erythropoeisis

A

RBCs die prematurely in bone marrow

34
Q

pancytopaenis can complicate severe megaloblastic anaemia, true or false

A

true

35
Q

nuclear maturation defects only effect red blood cells, true or false

A

false, it can affect al lineages

36
Q

in someone with macrocytic anaemia, if you did a bone marrow aspirate, would it be hypo/normo/hypercellular and why

A

hypercellular
there is a problem of cell division where you either produce large progeny or cells undergo apoptosis so there is a lot of premature red cell death
hypoxia is detected by kidneys which release EPO which increases cell turnover. There is a lot of activity in the bone marrow, but not much to show for it.

37
Q

why might you get jaundice in megaloblastic macrocytic anaemia

A

defective cell division means there is also premature RBC destruction IN THE MARROW and apoptosis of cells, this releases Hb which is broken down to bilirubin causing icterus/jaundice

Haematology (26 decks)

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