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3 HAEM > ITS BOARDS > Flashcards

ITS BOARDS Flashcards

1
Q

define hypo proliferative anaemia

A

bone marrow contains an inadequate number of red cell precursors (erythroblasts)

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2
Q

define ineffective erythropoiesis

A

despite normal or increased numbers of bone marrow erythroblasts, they produces a reduced number of normal cells

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3
Q

define haemolytic/haemorrhagic anaemia

A

shortened red cell survival

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4
Q

what are the most common causes of anaemia

A

inflammation
iron deficiency
acute bleeding

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5
Q

what are less common causes of anaemia

A

disorders of bone marrow stroma
disorders of stem cells
maturation disorders
haemolytics anaemias

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6
Q

when might a bone marrow biopsy aid diagnosis and why

A

when retic count is low, it may help differentiate between hypo proliferative and maturation disorders

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7
Q

why is bone marrow biopsy not indicated if retic count is high

A

the marrow is clearly capable of producing cells, but they are not surviving normally in circulation

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8
Q

in what types of anaemia is the retic count high

A

haemolytic

haemorrhagic

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9
Q

in what types of anaemia is the retic count low

A

hypoproliferative

maturation disorders

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10
Q

what are reticulocytes

A

young red blood cells that have been formed by extrusion of the erythroblast nucleus

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11
Q

why do retics stain slightly blue

A

they contain RNA/ribosomes

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12
Q

what is the normal percentage of retics in blood

A

1%

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13
Q

retic count increases in proportion to

A

the amount of erythropoiesis in the bone marrow

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14
Q

what dye is used to stain reticulocytes

A

brilliant cresyl blue

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15
Q

what is a more accurate measure of red cell production in anaemia; retic percentage or absolute retic count

A

the absolute retic count

the percentage will be skewed as there is a reduced number of red cells

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16
Q

what can cause decreased production of Hb or red cells

A

iron deficiency anaemia
megaloblastic anaemia
aplastic anaemia

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17
Q

what can cause premature loss or destruction of red cells

A 
haemolytic anaemias (autoimmune, inherited red cell defects)
bleeding
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18
Q

where is the majority of iron in the body located

A

in red cells (Hb)

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19
Q

what are the three main compartments of body iron

A

iron stores
transport iron
red cell iron

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20
Q

how is iron stored

A

ferritin

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21
Q

how is iron transferred in the plasma and why

A

transferrin

must be bound to a protein to prevent oxidative damage

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22
Q

what is the best measure of iron supply tot tissues

A

total iron binding capacity

saturation of the serum transferrin

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23
Q

how many iron molecules can bind to each transferrin molecule

A

2

24
Q

what type of iron is present in the diet

A

ferric (Fe3+)

25
Q

how is iron status assessed

A

functional iron in red cells (Hb)

storage iron in the form of ferritin

26
Q

what are the levels of iron stores, iron supply to tissues and red cell iron if there is reduced intake or increased loss of iron

A

iron stores: reduced

iron supply to tissues: normal

red cell iron: normal

27
Q

what are the levels of iron stores, iron supply to tissues and red cell iron if iron stores are depleted

A

iron stores: reduced

iron supply to tissues: reduced

red cell iron: normal

28
Q

what are the levels of iron stores, iron supply to tissues and red cell iron if iron deficient erythropoiesis is occurring

A

iron stores: reduced

iron supply to tissues: reduced

red cell iron: reduced

29
Q

what are the common causes of iron deficiency in developing and developed countries

A

developing countries

  • blood loss (GI bleeding)
  • diet

developed countries

  • rapid growth (infants, young children, adolescents)
  • women of childbearing age (menstrual blood loss, pregnancy)
30
Q

what are the clinical effects of iron deficiency

A

anaemia
epithelial abnormalities
impaired lymphocyte function and immune response

31
Q

what epithelial abnormalities are associated with iron deficiency

A 
buccal mucosal atrophy 
gastro mucosal atrophy 
post cricoid web
koilonychia 
angular cheilitis
32
Q

what is the basic structure of Hb

A

4 globin molecules; 2 alpha, 2 beta

4 haem molecules

33
Q

what mutation causes sickle cell anaemia

A

substitution of valine for glutamic acid at codon 6 or beta globin gene
(point mutation in beta gene)

34
Q

what types of Hb can be produced in homozygotic sickle cell

A

HbS

variable amount of HbF

35
Q

what causes red cell sickling

A

intracellular dehydration

36
Q

what is the molecular structure of HbS

A

a2bs2

37
Q

what are clinical features of sickle cell anaemia

A

anaemia
painful crises
rarely aplastic crises, stroke, priapism

38
Q

how do painful crises occur in sickle cell

A

sickled red cells produce microvascular obstruction and ischaemia

crises precipitated by cold, infection, dehydration

39
Q

how many alpha genes are there in each cell

A

4

40
Q

what genotypes can result in heterozygotic alpha thalassaemia

A

single gene deletion (a-/aa)

two gene deletion (–/aa)

41
Q

what clinical features are present in single/two gene deletion alpha thalassaemia

A

no clinical features

42
Q

what does a three alpha gene deletion cause

A

HbH disease with chronic haemolysis

43
Q

what are HbH molecules

A

beta chan tetramers (ie contain no alpha globin chains)

44
Q

what is hydrops fetalis

A

four alpha gene deletion

lethal

45
Q

what are signs of heterozygotic beta thalassaemia

A

high HbA2
low MCV
increased red cell count
clinically asymptomatic

46
Q

which Hb molecules are present in homozygotic beta thal

A

no HbA
mostly HbF
some HbA2

47
Q

what does does precipitation of alpha-globin in erythroid cells produce in beta thal

A

ineffective erythropoiesis and extra medullary haematopoiesis

48
Q

what is meant by beta thal trait

A

heterozygotic carriers of the mutation but with no symptoms

49
Q

how are haemoglobin disorders screened for

A

neonatal: heel prick/cord blood
preconceptual: in at risk populations
antenatal: selective

50
Q

what are complications of extra medullary haematopoiesis

A

enlargement of other bones eg maxilla, frontal bossing

iron accumulation

51
Q

what are causes of haemolysis

A

hereditary (enzymatic, membrane disorder, globin disorder)

acquired (immune, non-immune)

52
Q

what are causes of immune haemolysis

A

autoimmune spherocytic

alloimmune: haemolytic disease of the newborn

ABO mismatch transfusion

53
Q

what are causes of non-immune acquired haemolysis

A

mechanical (prosthetic heart valve, DIC)

infection (malaria)

chemical/physical (oxidative stress, burns)

membrane: liver disease

54
Q

what are diagnostic tests for haemolysis

A

direct Coombs test (detects antibodies bound to RBCs)

osmotic fragility (increased membrane fragility is spherocytosis)

G6PD enzyme activity screening test (quantitates production of NADPH)

55
Q

what are causes of inherited haemolysis

A

enzymes (G6PD)

membrane defects (spherocytosis, ellipocytosis)

3 HAEM (20 decks)

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