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Year 3 > Red Cells > Flashcards

Red Cells Flashcards

1
Q

what is anaemia?

A

the reduction in red cells or their haemoglobin content

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2
Q

main causes of anaemia

A

blood loss
increased destruction
lack of production
defective production

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3
Q

describe the development of red cells

A

see notes

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4
Q

what substances are required for red cell production?

A

metals - iron, copper, cobalt, manganease
vitamina -B12, folic acid,thiamine, B6, C, E
amino acids
hormones - erythropoietin, GM-CSF, androgens, thyroxine, SCF

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5
Q

normal life span of RBC

A

120 days

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6
Q

where does red cell breakdown take place?

A

in macrophages of reticuloendothial system

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7
Q

what happens to haem after red cell breakdown?

A

converted to biliverdin and bilirubin

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8
Q

what happens to globin and iron after red cell breakdown?

A

reutilised

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9
Q

describe the bilirubin cycle

A

see notes

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10
Q

defects in what parts of RBCs cause congenital anaemia

A

membrane
enzymes
haemoglobin

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11
Q

most congenital anemias result in what?

A

haemolysis

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12
Q

what are skeletal proteins in RBCs responsible for?

A

maintaining red cell shape and deformability

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13
Q

what can defects in the RBC cells membrane proteins caused?

A

increased cell destruction - haemolysis

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14
Q

what proteins are most commonly mutated in red cell membranes?

A

ankyrin
band 3
spectrin

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15
Q

draw a RBC membrane

A

see notes

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16
Q

Hereditary spherocytosis: inheritance

A

autosomal dominant

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17
Q

Hereditary spherocytosis: structural protein defects

A 
ankyrin
alpha spectrin
beta spectrin
band 3
protein 4.2
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18
Q

Hereditary spherocytosis: shape of cells

A

spherical

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19
Q

Hereditary spherocytosis: how are cells removed from circlulation?

A

haemolysis extravascular by spllen

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20
Q

Hereditary spherocytosis: clinical presentation

A

anaemia
jaundice (neonatal)
splenomegaly
pigment gallstones

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21
Q

Hereditary spherocytosis: treatment

A

folic acid
transfusion
splenectomy

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22
Q

name 3 rare membrane disorders

A

hereditary elliptocytosis
hereditary pyropoikilocytosis
South East Asian Ovalocytosis

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23
Q

name 2 cycles occuring in red cells. how are they linked?

A

gylcolysis
pentose phosphate shunt
glucose-6-phosphate dehydrogenase

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24
Q

in RBCs what is the purpose of glycolysis?

A

provides energy

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25
Q

in RBCs what is the purpose of the pentose dehydrogenase shunt?

A

protects from oxidative damage

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26
Q

what protects red cell proteins from oxidative damage?

A

glucose 6 phosphate dehydrogenase (G6PD)

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27
Q

what does G6PD produce?

A

NADPH

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28
Q

what is NADPH vital for?

A

reduction of glutathione

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29
Q

what does reduced glutathion do?

A

scavenges and detoxifies reactive oxygen species

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30
Q

what is the commonest disease causing enzymopathy in the world?

A

G6PD deficiency

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31
Q

what does G6PD deficiency result in?

A

cells vulnerable to oxidative damage

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32
Q

where is G6PD most common and why?

A

malarial areas as confers protection against severe falciparum

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33
Q

inheritance in G6PDdeficiency

A

x linked

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34
Q

what characteristics are there of RBCs in G6PD deficiency?

A

blister and bite cells

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35
Q

where does haemolysis occur in G6PD deficiency, what is the problem with this?

A

intravascular

haemoglobin can reach kidneys

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36
Q

clinical presentation of G6PD deficiency

A

neonatal jaundice
drug, broad bean or infection precipitated jaundice and anaemia
splenomegaly
pigment gall stones

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37
Q

triggers to haemolysis in G6PD deficiency

A

infection
acute illness e.g. DKA
broad beans “favism”

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38
Q

what drugs can cause G6PD deficiency?

A 
o	Antimalarials – primaquine, pamaquine
o	Sulphonamides and sulphones – salazopyrin, dapson, seprtin
o	Antibacterials – nitrofurantoin
o	Analgesics – aspirin
o	Antihelminths – B-naphthol
o	Vitamin K analogues
o	Probenecid 
o	Methylene blue
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39
Q

name a rare enzyme deficiency disorder and briefly describe it

A

o Reduced ATP
o Increased 2,3,-DPG
o Cells rigid
o Variable severity – anaemia, jaundice, gallstones
o More liable to haemolysis in circulation

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40
Q

in deoxyhaemoglobin what enzyme holds it in the tight binding structure?

A

2,3-DPG

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41
Q

function of haemoglobin

A

gas exchange

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42
Q

affinity of foetal haemoglobin (HbF) for oxygen compared to HbA

A

higher

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43
Q

describe the structure of normal adult haemoglobin

A

2 alpha chains
4 alpha genes, Chr16

2 beta chains
2 beta genes, Chr11

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44
Q

describe the composition of haemoglobin in a normal adult

A

HbA (aabb) - 97%
HbA2 (aadd) - 2%
HbF (aayy) - 1%

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45
Q

what are haemoglobinopathies?

A

inherited abnormalities of haemoglobin synthesis

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46
Q

what is thalassaemia?

A

reduced or absent globin chain production

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47
Q

give examples of mutations that lead to structurally abnormal globin chains

A 
HbS (sickle)
HbC
HbD 
HbE
HbO Arab
48
Q

inheritance of haemoglobinopathies

A

autosomal recessive

49
Q

structure of sickle haemoglobin

A

haem
2 alpha chains
2 beta (sickle) chains

50
Q

what mutation leads to sickle beta chains

A

point mutation - glutamate to valine

51
Q

describe the consequences of sickle cell

A

red cell injury, cation loss, dehydration

52
Q

describe the process of vaso-occlusion in sickle cell

A 
haemolysis
endothelial activation
promotion of inflammation
coagulation activation
dysregulation of vasomotor tone by vasodilator mediations (NO)
vaso occlusion
53
Q

describe polymerisation in sickle cell

A

Some of the major complications of sickle cell disease (SCD) such as acute chest syndrome, stroke and pain episodes are attributed to vasoocclusive tissue damage. Cerebral vasculopathy is a major risk factor for stroke. The primary pathophysiologic mechanisms for lung disease are unknown. Pulmonary vasculopathy may be a risk factor for acute chest syndrome pulmonary hypertension. Both are leading causes of morbidity and mortality in adults with sickle cell disease.

54
Q

sickle cell presentation

A 
retinopathy
cardiomegaly - congestive HF
cholelithiasis
renal infarcts - haematuria
bone marrow hyperplasia
aseptic bone necrosis - osteomyelitis
ulcer
vaso-occlusion
infarcts of extremities
splenomegaly - splenic atrophy
pulmonary infarcts -pneumonia
cerebral infarcts - stroke - mental retardation
55
Q

complications of sickle cell

A 
•	Painful vaso-occlusive crises
o	Bone
•	Chest crisis
•	Stroke
•	Increased infection risk
o	Hyposplenism – splenic infarction and atrophy
•	Chronic haemolytic anaemia
o	Gallstones
o	Aplastic crisis – eyrthrovirus 
•	Sequestration crises
o	Spleen – children, pooling of RBCs and not getting out, enlarged spleen
o	Liver – enlarged liver
•	Life expectancy
o	Males 42
o	Females 48
o	Childhood and perinatal mortality contribute to this reduction
56
Q

treatment of a painful crisis in sickle cell

A 
•	Severe pain – often requires opiates
o	Analgesia should be given within 30 mins of presentation
o	Effective analgesia by 1 hour
o	Avoid pethidine
•	Hydration
•	Oxygen
•	Consider
•	Antibiotics
•	No routine role for transfusion
57
Q

describe a chest crisis in sickle cell

A
  • Life threatening
  • Chest pain
  • Fever
  • Worsening hypoxia
  • Infiltrates on CXR
  • Respiratory support
  • Antibiotics
  • IV fluids
  • Analgesia
  • Transfusion – top up or exchange target HbS < 30%
  • Incentive spirometry shown to reduce incidence
58
Q

management of sickle cell

A 
•	Lifelong prophylaxis
o	Vaccination
o	Penicillin and malarial prophylaxis
o	Folic acid
•	Acute events
o	Hydration
o	Oxygenation
o	Prompt treatment of infection
o	Analgesia
	Opiates
	NSAIDs 
•	Blood transfusion
o	Episodic and chronic
o	Alloimmunisation
o	Iron overload
•	Disease modifying drugs
o	Hydroxycarbamide
•	Bone marrow
o	Transplantation 
o	Severe 
•	Gene therapy
o	Severe
59
Q

thalassaemia can result from mutations/delections in

A

alpha genes
beta genes
also gamma and delta but less important

60
Q

thalassaemia results in

A

chain imbalance - chronic haemolysis and anaemia

61
Q

spectrum of thalassaemia from fatal to minor

A

homozygous alpha zero thalassaemia
thalassaemia major
thalassaemia intermedia
thalassaemia minor

62
Q

what is homozygous alpha zero thalassaemia

A

no alpha chains

hydrops fetalis - incompatible with life

63
Q

what is beta thalassaemia major

A

no beta chains

transfusion dependent anaemia

64
Q

when may someone with thalassaemia intermedia require transfusions?

A

times of stress

65
Q

what is thalassaemia minor?

A

carrier
hypochromic microcytic cells
asymptomatic

66
Q

severe anaemia in beta thalassaemia major results in

A

o Expansion of ineffective bone marrow
o Bony deformities
o Splenomegaly
o Growth retardation

67
Q

when does beta thalassaemia major present?

A

3-6months

68
Q

treatment of beta thalassaemia major

A

chronic transfusion
iron chelation therapy
bone marrow transplant

69
Q

how often do those with beta thalassaemia major require blood transfusions? what can this cause?

A

4-6 weekly

iron overloading

70
Q

consequences of iron overloading

A

death in 2nd/3rd decade due to heart/liver/endocrine failure if unteated

71
Q

describe iron chelation therapy

A

 s/c deferrioxamine infusions (Desferal)
 Oral deferasirox (exjade)
 If good adherence life expectancy >40

72
Q

describe rare defects in haem synthesis

A

Defects in mitochondrial steps of haem synthesis result in sideroblastic anaemia. ALA synthase mutations. X linked inheritance. Acquired myelodysplasia. Defects in cytoplasmic steps result in porphyrias.

73
Q

what factors influence normal haemoglobin?

A 
age
sex
ethnic origin
time of day
time to analysis
74
Q

normal haemoglobin: male 12-70

A

140-180

75
Q

normal haemoglobin: male > 70

A

116-156

76
Q

normal haemoglobin: female 12-70

A

120-160

77
Q

normal haemoglobin: female >70

A

108-143

78
Q

clinical features of acquired anaemia are due to?

A

reduced oxygen delivery to tissues

79
Q

clinical features of acquired anaemia

A 
tiredness/pallor
breathlessness
swelling of ankles
dizziness
chest pain
80
Q

clinical features of acquired anaemia related to underlying cases

A

evidence of bleeding
symptoms of malabsorption - diarrhoea, weight loss
jaunice
splenomegaly/lymphadenopathy

81
Q

potential causes of anaemia due to bleeding

A

menorrhagia
dyspepsia
PR bleeding

82
Q

what further tests would you do in a hypochromic microcytic anaemia?

A

serum ferritin

83
Q

what further tests would you do in a normochromic normocytic anaemia?

A

reticulocyte count

84
Q

what further tests would you do in a macrocytic anaemia?

A

B12/folate

bone marrow

85
Q

most common cause of hypochromic microcytic anaemia?

A

iron deficiency

86
Q

hypochromic microcytic anaemia, serum ferritin = low

A

iron deficiency

87
Q

hypochromic microcytic anaemia, serum ferritin = normal/increased

A

secondary anaemia
thalassaemia
sideroblastic anaemia

88
Q

describe iron metabolism

A

Transferrin can contain up to two atoms of iron. Transferrin delivers iron to tissues that have transferrin receptors, especially erythroblasts in the bone marrow which incorporate the iron into haemoglobin. At the end of the red cell life cycle, the red cells are broken down in the macrophages of the reticuloendothelial system and the iron is released from haemoglobin, enters the plasma and is reutilised to provide most of the iron on transferrin. Only a small proportion of plasma transferrin iron comes from dietary iron, which comes in via the duodenum and jejunum. Some iron is stored in the macrophages as ferritin and haemosiderin, which varies depending on overall body iron status. Iron is also present in the muscle as myoglobin and in most other cells of the body in iron-containing enzymes e.g. cytochromes, succinic dehydrogenase, catalase. Body has no way of getting rid or iron hence why it builds up in transfusions

Hepcidin goes up in menstruation, inflammation and renal impairment to stop utilising iron. Iron absorbed in duodenum - Fe2+ > Fe3+. Transported from enterocytes and. macrophages by ferroportin. Transported in plasma bound to transferrin. Stored in cells as ferritin. Hepcidin synthesised in hepatocytes in response to inflammation (also renal failure and ↑iron levels)– blocks ferroportin so reduces intestinal iron absorption and mobilisation from reticuloendothelial cells.

89
Q

causes of iron deficiency

A 
dyspepsia, GI bleeding
menorrhagia
diet 
increased requirement e.g. pregnancy
malabsorption
90
Q

what may cause malabsorption of iron?

A

gastrectomy

coeliac disease

91
Q

principles of management in iron deficiency

A

correct the deficiency

correct the cause

92
Q

how to correct iron deficiency

A

oral iron
IV if intolerant of oral
transfusion rarely indicated

93
Q

how to correct the cause of iron deficiency

A

diet
ulcer therapy
gynae interventions
surgery

94
Q

nomochromic normocytic anaemia, reticulocyte count = increased

A

blood loss

haemolysis

95
Q

nomochromic normocytic anaemia, reticulocyte count = normal/low

A

secondary anaemia
hypoplasia
marrow infiltration

96
Q

results of haemolytic anaemia

A

accelerated red cell destruction - decreased haemoglobin

compensated by bone marrow - increased reticulocytes

97
Q

causes of haemolytic anaemia: congenital

A

hereditary spherocytosis
enzyme deficiency G6PD def
haemoglobinopathy - sickle cell

98
Q

causes of haemolytic anaemia: acquired

A

autoimmune haemolytic anaemia
mechanical e.g. artificial valve
sever infections/DIC
PET/HUS/TTP

99
Q

extra vs intravascular. acquired haemolytic anaemia - immune related

A

extravascular

100
Q

extra vs intravascular. acquired haemolytic anaemia - non-immune related

A

intravascular

101
Q

in haemolytic anaemia what does it mean if DAGT is positive?

A

immune related

102
Q

causes of acquired immune haemolysis + warm auto antibody

A

auto immune
drugs
CLL

103
Q

causes of acquired immune haemolysis +cold autoantibody

A

CHAD
infections
lymphoma

104
Q

causes of acquired immune haemolysis + alloantibody

A

transfusion reaction

105
Q

how do you determine if a patient is haemolysing?

A

o FBC, reticulocyte count, blood film
o Serum bilirubin (direct/indirect), LDH
o Serum haptoglobin

106
Q

how do you determine the cause of haemolysis?

A

o History and examination
o Blood film
o Direct antiglobulin test (Coombs’ test)
o Urine for haemosiderin/urobilinogen -intravascular haemolysis

107
Q

management of haemolytic anaemia

A 
•	Support marrow function
o	Folic acid
•	Correct cause
o	Immunosuppression if autoimmune
	Treat trigger e.g. CLL , lymphoma
o	Remove site of red cell destruction
	Splenectomy
o	Treat sepsis, leaky prosthetic valve, malignancy etc if intravascular
•	Consider transfusion
108
Q

secondary anaemia aka

A

anaemia of chronic disease

109
Q

secondary anaemia is mostly what type?

A

normochromic normocytic

110
Q

what causes secondary anaemia?

A

Defective iron utilisation as a result of increased hepcidin in inflammation. Ferritin is often elevated. Identifiable underlying disease – infection, inflammation, malignancy.

111
Q

causes of megalblastic macrocytic anaemia

A

B12/folate deficiency

112
Q

causes of non-megaloblastic macrocytc anaemia

A

myelodysplasia
marrow infiltration
drugs

113
Q

causes of B12 deficiency

A

pernicious anaemia

gastric/ileal disease

114
Q

causes of folate deficienc

A

dietary
increased requirements e.g. haemolysis
GI pathology e.g. coeliac

115
Q

how is B12 absorped?

A

dietary B12 binds to intrinsic factor, secreted by gastric parietal cells. B12-IF complex attaches to specific IF receptors in distal ileum. Vit B12 bound by transcobalamin II in portal circulation for transport to marrow and other tissues

116
Q

mechanism of pernicious anaemia

A

It is an autoimmune disease. Antibodies against intrinsic factor (diagnostic) and gastric parietal cells. There is malabsorption of dietary B12, but the signs and symptoms take around 1-2 years to develop.

117
Q

causes of non-megaloblastic macrocytosis

A 
•	Alcohol
•	Drugs
o	Methotrexate, antiretrovirals, hydroxycarbamide
•	Disordered liver function
•	Hypothyroidism
•	Myelodysplasia

Year 3 (164 decks)

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