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Paediatrics > 1: Haematology - Sickle Cell Disease > Flashcards

1: Haematology - Sickle Cell Disease Flashcards

1
Q

What is sickle cell disease

A

Autosomal recessive haemaglobinotpathy where individuals have HbSS

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2
Q

What is sickle cell trait

A

HbSA

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3
Q

What ethnicities is sickle cell more common

A

African-American

East- Medeteranian

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4
Q

What is the inheritance pattern of sickle cell

A

Autosomal Recessive

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5
Q

What causes sickle cell anaemia

A

Mutation in position-6, chromosome 11. Where valine replaces glutamic acid

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6
Q

What chromosome is affected in sickle cell anaemia

A

Chromosome 11

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7
Q

What amino acid is mutated in sickle cell anaemia

A

Valine replaces Glutamic acid

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8
Q

What kind of mutation happens in sickle cell

A

Non-conservative mis-sense mutation

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9
Q

What is a risk factor for sickle cell disease

A

FH

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10
Q

Explain advantage of sickle cell disease and trait

A

Sickle cell trait is advantageous against Malaria Falciparum

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11
Q

Explain presentation of sickle-cell

A

Sickle cell is characterised by period of good health with intervening crisis

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12
Q

What is vase-occlusive crisis also known as

A

Pain crisis

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13
Q

In which age group does vase-occlusive crisis usually present

A

Childhood

Adolescence

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14
Q

Explain presentation of vase-occlusive crisis in children

A

Presents with dactylitis and bone pain

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15
Q

What happens with vaso-occlusive crisis

A

Becomes more central with age can lead to acute chest syndrome and stroke

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16
Q

What is acute chest syndrome is type of

A

Vaso-occlsuive crisis

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17
Q

What are 3 triggers of vase-occlusive crisis

A

Dehydration
Infection
Deoxygenation

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18
Q

What is acute chest syndrome

A

When there is vaso-occlusion of pulmonary vasculature

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19
Q

How does acute chest syndrome present

A
  • Chest pain
  • Breathlessness
  • Reduced SpO2
  • Fever
  • Respiratory distress
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20
Q

What is the most common cause of death in sickle cell disease

A

Acute chest syndrome

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21
Q

What are 3 triggers of acute chest syndrome

A

GA
Asthma
Infection

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22
Q

What is splenic sequestration

A

Vaso-occlusion of spleen causes entrapment of blood and pooling of large amounts of blood in the spleen

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23
Q

In which age is splenic sequestration more common

A

First year of life

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24
Q

How does splenic sequestration present clinically

A
  • LUQ pain
  • Symptoms intravascular haemolysis: hypotension
  • Rapid anaemia
  • Reticulocytosis
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25
Q

Aside from splenic sequestration, what other organs may be affected

A

Later liver and lung

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26
Q

What can splenic sequestration cause over time and what does this mean

A

Autosplenectomy: causes fibrosis of the spleen and necrosis. This means spleen cannot function predisposing to infection with capsulated bacteria

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27
Q

What are some capsulated bacteria

A

H. Influenza
S. Pneumonia
N. Meningitdis

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28
Q

What is an aplastic crisis

A

Sickle cell patient is infected with parvovirus B19

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29
Q

How does parvovirus B19 cause aplastic crisis

A

When parvovirus B19 infects reticulocytes it prevents proliferation.In normal individuals there is sufficient supply RBC to be asymptomatic. In sickle cell, as there is already haemolysis, can present with symptoms

30
Q

When can sickle-cell cause stroke

A

Most common 5-10 years. Can occur up to 20 year-olds

31
Q

What % of strokes in sickle-cell are asymptomatic

A

20%

32
Q

How is stroke in sickle-cell disease managed

A

Plasma exchange transfusion

33
Q

When does functional hyposplenism in sickle cell usually occur and what does this cause

A

By 1-year, predisposing to infection with capsulated bacteria

34
Q

What % of individuals have priapism in sickle-cell

A

3-4% pre-pubertal

40% post-pubertal

35
Q

What MSK conditions can sickle-cell lead to

A

Avascular necrosis

36
Q

What are two renal complications of sickle-cell

A

Papillary necrosis - causes haematuria

Hyposthenuria = inability to concentrate urine

37
Q

What are other complications of sickle-cell disease

A

Enlarged tonsillar- adenoids = can lead to OSA

38
Q

How does sickle cell trait present

A

Asymptomatic, unless in low oxygen concentration

39
Q

What is HbA (adult haemoglobin) made up of

A

HbA is made of two alpha and two beta chains

40
Q

What mutation happens in sickle cell disease and what does this cause

A

Non conservative mis-sense mutation in position 6 at chromosome 11

41
Q

What is a non-conservative mutation

A

New amino acid formed has different properties to other amino acid

42
Q

What is a mis-sense mutation

A

single base substitution causes new amino acid

43
Q

What base is substituted in sickle cell disease

A

Valine replaces glutamic acid in position 6

44
Q

Is glutamic acid hydrophillic or hydrophobic

A

Hydrophilic

45
Q

Is valine hyrophillic or hydrophobic

A

Hydrophobic

46
Q

What does individual require for sickle cell

A

Two mutated B-globin genes to given HbSS

47
Q

Explain traits of HbSS

A

HbSS is normal when oxygenated. However when deoxygenated it can aggregate together forming long polymers that distort RBC shape = sickling

48
Q

What factors favour sickling

A

Favours the reduce affinity of Hb with oxygen including acidosis and low flow vessels

49
Q

Explain impact of sickling

A

Repeated sickling causes damage to RBC membranes which triggers intravascular haemolysis.

50
Q

What is an indicator of intravascular haemolysis

A

Low haptoglobin

51
Q

Why is haptoglobin low in intravascular haemolysis

A

Hb released from RBC in intravascular haemolysis binds to haptoglobin

52
Q

What type of bilirubin is present in intravascular haemolysis

A

Unconjugated bilirubin

53
Q

What happens to bone marrow

A

Low Hb stimulates reticulocytosis of bone marrow which causes expansion of medullary (bone-marrow) cavities which can cause a hair on end appearance

54
Q

What test is performed for all neonates in the UK

A

Neonatal heel prick test (5-9d)

55
Q

If Gunthrie test is positive, what is performed

A

Hb Electrophoresis

56
Q

What should happen to all afro-carribean individuals before surgery and why

A

Screen for sickle cell prior to giving GA - as can precipitate acute chest crisis

57
Q

What screening happens in all individuals with sickle cell

A

Annual cranial US to check for high resistance - which can indicate stroke. If present require plasma exchange

58
Q

What diagnostic tests may be ordered in sickle cell

A

FBC
Peripheral Blood Smear
Hb Electrophoresis

59
Q

What will be seen on FBC in sickle cell

A

Anaemia

Reticulocytosis

60
Q

What will be seen on peripheral blood smear in sickle cell

A

Howell Jolly Bodies

61
Q

How is an acute crisis managed in sickle cell

A
  • Oxygen
  • IV Fluids
  • Keep warm
  • Analgesia

May require:

  • Exchange transfusion
  • Blood transfusion
62
Q

When is exchange transfusion ordered

A

if acute chest syndrome, neurological complications

63
Q

When is a blood transfusion ordered in sickle cell

A

aplastic anaemia

64
Q

What is given as maintenance in sickle cell

A

hydroxyurea

65
Q

What is the MOA of hydroxyurea in sickle cell

A

increases foetal Hb

66
Q

What indicates compliance with hydroxyurea

A

Macrocytosis

67
Q

What is a side-effect of hydroxyurea

A

Bobe marrow suppression

68
Q

What is given as prophylaxis in sickle cell under 5-years old and why

A

Penicillin V = to prevent against infection with capsulated bacteria

69
Q

What is given daily in sickle cell

A

Folic acid: to replenish RBC stores

70
Q

What is the only curative treatment in sickle cell

A

Allogenic bone marrow transplant

Paediatrics (61 decks)

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