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Haematology HK > Anaemias > Flashcards

Anaemias Flashcards

1
Q

what is haematocrit

A

%RBC of blood volume

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2
Q

in what scenarios is Hb not a good indicator of anaemia

A

if the patient has lost a large volume of blood

if the patient has been given saline fluids

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3
Q

what are the 2 classifications of anaemia

A

microcytic

macrocytic

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4
Q

what determines if an anaemia is microcytic or macrocytic

A

mean cell volume
low = microcytic (small erythrocytes, less of them)
high = macrocytic (big erythrocytes, less of them)

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5
Q

where in the erythrocyte is Hb synthesised

A

cytoplasm

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6
Q

microcytic erythrocytes have high/low volumes of Hb

A

low

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7
Q

what kind of anaemia is caused by lack of raw materials

A

microcytic

less Hb made, cells are smaller

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8
Q

what are features of Hb deficient microcytic erythrocytes

A

hypochromic - lacking in red colour
pencil cells
target cells

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9
Q

what might cause iron deficiency

A

heavy periods (blood loss)
lack of dietary iron (uncommon in this country)
anaemia of chronic disease - iron levels normal, not bioavailable
GI blood loss
malabsorption of iron (e.g. coeliac)

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10
Q

what might cause porphyrin deficiency

A

lead poisoning

pyridoxine responsive anaemia

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11
Q

what might cause globin deficiency

A

thalassaemia

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12
Q

if a patient has lost 1L blood, how much iron have they lost

A

500ml

iron loss = 1/2 blood loss

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13
Q

where is iron stored

A

macrophages (from RBC breakdown)
liver
haemoglobin

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14
Q

where does most iron exist

A

Hb

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15
Q

what is circulating iron bound to

A

transferrin

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16
Q

when is %saturated transferrin decreased

A

iron deficiency

anaemia of chronic disease

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17
Q

when is %saturated transferrin increased

A

haemachromatosis

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18
Q

how is iron stored in liver

A

as ferritin

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19
Q

how do you measure storage iron

A

serum ferritin

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20
Q

how is iron deficiency confirmed

A

combination of low Hb (functional iron) and low serum ferritin (low storage iron)

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21
Q

where is dietary iron absorbed from

A

proximal small bowel

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22
Q

what are the 2 true causes of macrocytic anaemia

A

megaloblastic

non-megaloblastic

23
Q

what is a megaloblast

A

abnormally large nucleated red cell precursor with an immature nucleus

24
Q

what is defective in megaloblastic macrocytic anaemias

A

DNA synthesis and nuclear maturation

preserved Hb and RNA synthesis

25
Q

why are megaloblasts bigger than normal cells

A

divides fewer times
however Hb still accumulates in cytoplasm eventually triggering enucleation
left with larger RBCs but less of them

26
Q

what are causes of megaloblastic macrocytic anaemias

A

B12 and folate deficiencies
Drugs
inherited abnormalities of enzymes

27
Q

why does B12 and folate deficiency cause megaloblastic anaemia

A

they provide enough nucleosides for DNA synthesis which allows DNA replication to occur

28
Q

what biochemical pathway does folate catalyse

A

uridine to thymidine

29
Q

what is the only source of B12

A

meat and animal food - cobalamine

30
Q

where is B12 released from food

A

stomach - acidic environment

31
Q

what binds to B12 and where

A

intrinsic factor

form a complex in proximal small bowel

32
Q

what secretes intrinsic factor

A

parietal cells in fundus and body of stomach

33
Q

where is the B12-intrinsic factor complex absorbed

A

terminal ilium

34
Q

what are causes of B12 deficiency

A

vegans
stomach problems - atrophic gastritis, pernicious anaemia
small bowel - coeliac, bacterial overgrowth, crohn’s

35
Q

what is pernicious anaemia

A

autoimmune condition resulting in destruction of gastric parietal cells

36
Q

consequences of ineffective gastric parietal cells

A

no intrinsic factor secreted

therefore B12 cannot be absorbed

37
Q

what are conditions associated with pernicious anaemia

A

other autoimmune conditions:
hypothyroid
vitiligo
Addison’s

38
Q

how is folate absorbed

A

dietary folates converted to monoglutamate

absorbed in jejunum

39
Q

what are sources of folate

A

leaf veg and yeast

40
Q

causes of folate deficiency

A

inadequate dietary intake
malabsorption - coeliac, crohn’s
excess utilisation - pregnancy, malignancy, exfoliating dermatitis, haemolysis
drugs - anticonvulsants

41
Q

folate/B12 is more likely due to inadequate dietary intake. Why?

A

Folate - stores are only last for 4 months

B12 stores last 2-4 years

42
Q

what are clinical features of both B12/folate deficiency

A 
anaemia
weight loss
diarrhoea 
infertility 
sore tongue jaundice 
developmental problems in children
43
Q

neurological problems can occur in B12/folate deficiency

A

B12

44
Q

why do neurological problems occur in B12 deficiency

A

B12 involved in the formation of myelin

45
Q

neurological manifestations of B12 deficiency

A

dorsal column abnormalities
neuropathy
dementia
psychiatric manifestations

46
Q

what might the blood film show in macrocytic anaemia

A

macrovalocytes and hypersegmented neutrophils (3-5 nuclear segments)

47
Q

what anti-bodies indicate pernicious anaemia

A

anti gastric-parietal cell (antiGPC)

anti intrinsic factor (antIF)

48
Q

what antibody is more specific to pernicious anaemia

A

antiIF

49
Q

what medication is given to treat B12 deficiency

A

hydroxycobalamin IM

loading dose for 2 weeks then three monthly life-long

50
Q

what medication is given to treat folate deficiency

A

folic acid 5mg/day oral

51
Q

when would you do a blood transfusion due to macrocytic anaemia

A

if life threatening

52
Q

what are causes of non-megaloblastic macrocytic anaemia

A

alcohol
liver disease
hypothyroid
bone marrow failure (myelodysplasia, myeloma, aplastic anaemia)

53
Q

why might MCV be measured as high when it is actually normal

A

increase in reticulocyte numbers as a response to acute blood loss

cold-agglutinins - clumps of agglutinated red cells which may register as one giant cell

54
Q

why might patients with pernicious anaemia appear mildly jaundiced

A

intramedullary haemolysis - causes premature red cell death. Results in release of Hb which is conveted to bilirubin

Haematology HK (22 decks)

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