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YEAR 5: HAEM > Haem: Paediatric haematology > Flashcards

Haem: Paediatric haematology Flashcards

1
Q

Which feature of children predisposes them to nutrient deficiency?

A

Rapid growth

deficinecy in Fe, B12 are common

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2
Q

How is the immune response to infection different in children compared to adults?

A

Children are more likely to mount a lymphocytosis as they frequently encounter new pathogens

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3
Q

What are the main differences between the blood count of neonate and an adult?

A
  • Higher WCC (neutrophils, lymphocytes)
  • Higher Hb - more HbF
  • Higher MCV
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4
Q

Why does beta thalassemia major not manifest at birth

A

will only present 3-6 months later when fetal haemoglboin decreases and production of HbA is not switched on

similarly sickle cell would not manifest until 3-6months later when HbF decreases and HbS increases but it is tested for at birth

alpha thalassemia does as it alpha globin needed for HbF

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5
Q

How are the enzyme levels in the red blood cells of neonates different to adults?

A

G6PD conc in neoates is 50% higher than in adults

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6
Q

List some causes of polycythaemia in a foetus.

A
  • Twin-to-Twin transfusion syndrome
  • Intrauterine hypoxia
  • Placental insufficiency
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7
Q

List some causes of anaemia in a foetus.

A
  • Twin-to-Twin transfusion syndrome - haemorrhage from one twin to another, one has anaemia, the other has polycthaemia
  • Foetal-to-Maternal transfusion - fetus bleeds into maternal circulation
  • Maternal Parvovirus infection
  • Bleeding from cord or placenta
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8
Q

List some causes of damage to the red blood cells of a foetus.

A
  • Irradiation
  • Damage by something crossing the placenta (e.g. drugs, antibodies)
  • Anticoagulants - warfarin
  • Substances in breast milk (e.g. fava beans in a baby with G6PD deficiency
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9
Q

When does the first mutation that leads to childhood leukaemia often occur?

A

In utero

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10
Q

Which condition is assocaited with congenital leukaemia?

A

Down syndrome

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11
Q

What is another term to describe congenital leukaemia?

A

Transient abnormal myelopoiesis (TAM)

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12
Q

Describe the usual course of congenital leukaemia.

A
  • Remits spontaneously within the first 2 months of life
  • However, 25% of infants will relapse after 1-2 years
  • NOTE: the leukaemia is myeloid with major involvement of the megakaryocyte lineage
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13
Q

Define thalassaemia.

A

A group of conditions resulting from a reduced rate of synthesis of one or more globin chains as a result of a genetic defect.

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14
Q

Define haemoglobinopathy.

A

Refers to a structurally abnormal haemoglobin.

NOTE: thalassemias are sometimes considered a form of haemoglobinopathy

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15
Q

On which chromosomes are the different globin genes expressed?

A

Chromosone 11

  • Beta
  • Delta
  • Gamma
  • Epsilon

Chromosone 16

  • 2x alpha
  • Zeta
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16
Q

Which globin chains are found in the following types of haemoglobin:

  1. HbA
  2. HbA2
  3. HbF
A
  1. HbA = 2 alpha, 2 beta
  2. HbA2 = 2 alpha, 2 delta
  3. HbF = 2 alpha, 2 gamma
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17
Q

What is the normal HbA2 level in a healthy adult?

A

< 3.5%

main one is HbA

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18
Q

Describe how the haemoglobin levels in utero change.

A
  • Some specific foetal haemoglobins (epsilon, zeta etc) are present in the first 16 weeks
  • HbF predominates throughout most of foetal life
  • After around 32 weeks, there is a rapid increase in HbA production
  • At birth, around 1/3 haemoglobin is HbA but this rapidly increases after birth
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19
Q

What is the difference between sickle cell anaemia and sickle cell disease?

A
  • Sickle cell anaemia - homozygosity for HbS gene
  • Sickle cell disease - encompasses homozygous and heterozygous states associated with sickling (including HbSC and HbS/beta thalassemia)
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20
Q

Outline the pathophysiology of sickle cell anaemia.

A
  • Hypoxia leads to polymerisation of HbS leading to crescent-shaped red blood cells and blocker blood vessels
  • This tends to occur in post-capillary venules
  • When passing through these venules, red cells tend to elongate
  • If the circulation slows down, cells will begin sickling and stickling to the endothelium causing obstruction
  • Retrograde capillary obstruction results in arterial obstruction
  • Early on, the sickling may be reversible by correcting the hypoxia
  • However, the cells can become irreversibly sickled
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21
Q

What feature of hyposplenism might you seeon a blood film of a patient with sickle cell anaemia?

A

Howell Jolly bodies

blue arrows - partially sickled, red arrow - sickled

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22
Q

Describe the severity of the following types of sickle cell disease:

  1. Sickle cell trait
  2. Sickle cell anaemia
  3. HbSC
  4. HbS/beta thalassemia
A
  1. Sickle cell trait
    • Usually asymptomatic
  2. Sickle cell anaemia
    • Manifests when HbF decreases and HbS increases (at 6 months age)
    • Severe symptoms
  3. HbSC
    • Slightly milder than sickle cell anaemia
    • 1 copy HbC, 1 copy HbS
    • HbC is abnormal but it is less abnormal than HbS
  4. HbS/beta thalassemia
    • Severity depends on whether it is beta-0 gene (no globin production) or beta+ gene (some globin production)
    • Will be microcytosis due to thalassemia
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23
Q

When is sickle cell anaemia usually diagnosed in the UK?

Why is this necessary

A

At birth following the Guthrie test

to prevent complications associated with sickle cell that occur in children e.g. hand/foot syndrome and splenic sequestration

mother also screened antenatally

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24
Q

Why does sickle cell anaemia in a child differ from sickle cell anaemia in an adult?

A
  • Mainly because the distribution of red bone marrow (contains haematopoietic precursors) differs
  • Red bone marrow is vascular, metabolically active and susceptible to infarction
  • Red marrow is in all bones in chilid, in adults confined to axial skeleton and ends of long bones
  • Bone pain due to infarction is a prominent clinical feature in sickle cell anaemia - risk in all bones
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25
Q

How is the pattern of bone pain due to infarction different in adults with sickle cell anaemia compared to children?

A
  • Adults - only happens in central skeleton
  • Infants/Children - can happen anywhere (including hands and feet causing hand-foot syndrome)

can be prevented if sickle cell diagnosed at birth

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26
Q

How is splenic function different in children with sickle cell anaemia compared to adults and what risks does this pose?

A
  • Children still have functioning spleens meaning that a child is much more likely to undergo splenic sequestration
  • This can lead to severe anaemia, shock and death
  • Teenagers and adults don’t tend to experience splenic sequestration because recurrent infarction has left their spleen small and fibrotic
  • However, as the risk of splenic sequestration declines with time, the risks of hyposplenism increase
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27
Q

Define splenic sequestration.

A

Acute pooling of a large percentage of circulating red cells in the spleen

28
Q

How is splenic sequestration managed?

A
  • Parents should be taught how to palpate the spleen and to seek help when the child is acutely unwell with a large spleen
  • Blood transfusion
29
Q

Which age groups tends to be affected by hand-foot syndrome?

A

< 2 years

30
Q

Which complication of sickle cell anaemia occur in younger children (2-10 years old)?

A
  • Acute chest syndrome (caused by infarction of the ribs and lungs)
  • Painful crises
  • Stroke (SCD is the most common cause of stroke in children)
31
Q

How does the susceptibility to bacteraemia change throughout the life of a patient with sickle cell anaemia?

A
  • Highest at younger ages irrespective of hyposplenism
  • Decreases with age
32
Q

Which infectious agents are children with sickle cell anaemia particularly vulnerable to?

A
  • Pneumococcus, haemophilus
  • Parvovirus B19 (causes aplastic anaemia)
  • malaria

encapsulated bacteria

33
Q

What medication and supplementation is need for sickle cell children

A
  • Vaccination
  • Prophylactic antibiotics - penicillin V 3months -5 years
  • Folic acid - increased need for haemopoeisis
34
Q

Why do children with sickle cell anaemia have increased folate demands?

A
  • Hyperplastic erythropoiesis
  • Growth spurts
  • Reduced red cell lifespan –> so become anaemic very quickly if they have folic acid deficiency
35
Q

What are the principles of managing sickle cell anaemia?

A
  • Educate parents
  • Vaccinate
  • Prescribe folic acid and penicillin
36
Q

Describe the difference in severity of beta thalassaemia trait and beta thalassaemia major.

A
  • Trait - harmless but genetically important (can impact children)
  • Major - severe anaemia that is tranfusion-dependent

NOTE: there is an intermediate form called beta-thalassaemia intermedia, not transfusion dependent but does cause anaemia

37
Q

List some clinical features of poorly controlled beta thalassaemia major.

A
  • Anaemia → heart failure, growth retardation
  • Erythropoietic drive → bone expansion, hepatomegaly, splenomegaly
  • Iron overload frorm transfusions → heart failure, gonadal failure
38
Q

What are the principles of treatment of beta thalassaemia major?

A
  • Accurate diagnosis and family counselling
  • Blood transfusion
  • Iron chleation
39
Q

List some types of inherited haemolytic anaemia.

A
  • Red cell membrane - hereditary spherocytosis, hereditary eliptocytosis
  • Haemoglobin molecule - sickle cell anaemia
  • Glycolytic pathway - pyruvate kinase deficiency
  • Pentose shunt - G6PD deficiency

haemolytic disease of newborn is congenital but not inherited

40
Q

What should you look for when investigating a patient with suspected haemolytic anaemia?

A
  • Is there anaemia?
  • Is there evidence of increased red cell turnover? (e.g. jaundice, splenomegaly)
  • Is there evidence of increased red cell production? (e.g. increased reticulocyte count, bone expansion)
  • Are there abnormal cells?
41
Q

Aside from the haemolysis, what else contributes to anaemia in sickle cell anaemia?

A
  • HbS has a low affinity for oxygen meaning that is releases oxygen readily to tissues
  • This reduces EPO-drive
42
Q

List some triggers for haemolysis in G6PD deficiency.

A
  • Infections
  • Drugs
  • Naphthalene
  • Fava/broad beans
43
Q

What is the inheritance pattern of G6PD deficiency?

A

X-linked recessive

44
Q

Cells on blood film in G6PD

A

Heinz bodies
bite cells

raised MCV - high reticulocytes

45
Q

What are the two main types of acquired haemolytic anaemia?

A
  • Autoimmune haemolytic anaemia
  • Haemolytic uraemic syndrome
46
Q

What are the characteristic features of autoimmune haemolytic anaemia?

A
  • Spherocytes
  • Positive DAT
47
Q

What happens in HUS
what is the cause

A
  • E.coli 0157:H7 –> bloody diarhoead
  • Shiga toxin –> thrombosis in small blood vessels
  • thromboctopenia, MAHA, AKI
  • MAHA - shearing of RBCs into fragments as they pass through fibrin strands within capillaries (intravascular haemolysis)
48
Q

What are the most common inherited defects of coagulation?

A
  • Haemophilia A - factor VIII deficiency
  • Haemophilia B - factor IX deficiency
  • Von Willebrand disease
49
Q

Describe the typical presentation of haemophilia A and B in an infant.

A
  • Bleeding following circumcision
  • Haemarthrosis when starting to walk
  • Post-traumatic bleeding

clinically A and B are indistinguishable - need to do factor assays

50
Q

List some differential diagnoses for haemophilia.

A
  • Inherited thrombocytopaenia/platelet defect
  • Acquired defects of coagultion (e.g. ITP, acute leukaemia)
  • Non-accidental injury
  • Henoch-Schonlein purpura
51
Q

What are some key aspects of investigating a child with a suspected defect of coagulation?

A
  • Family history
  • Coagulation screen
  • Platelet count
  • Assays for specific coagulation factors
52
Q

APTT and PT in haemophilia

A

prolonged APTT - intrinsic pathway

normal PT - extrinsic pathway

53
Q

List some specific details of an infant’s early history that could be suggestive of a disorder of coagulation.

A
  • Bleeding from the umbilical cord
  • Bleeding after the Guthrie test
  • Haematoma formation after vitamin K injection/vaccines
  • Bleeding after circumcision
54
Q

What are the principles of treatment of inherited disorders of coagulation?

A
  • Counselling the family
  • Treatment of bleeding episodes
  • Use of prophylactic coagulation factors
55
Q

Describe the typical presentation of von Willebrand disease.

A
  • Mucosal bleeding
  • Bruises
  • Post-traumatic bleeding

as platelets are affected

56
Q

Inheritance pattern of haemophilia

A

X-linked recessive

57
Q

Why do von Willebrand disease and haemophilia A present similarly?

A

They are both characterised by low level of factor 8

58
Q

How is von Willebrand disease diagnosed?

A
  • Family history (mainly autosomal dominant(
  • Coagulation screen
  • Factor 8 assay
  • Bleeding time
  • Platelet aggregation studies
59
Q

How is von Willebrand disease treated?

A

Lower purity factor 8 concentrates

as this also contains vwF

60
Q

Describe the relative prevalence of haemophilia A and B.

A

Haemophilia A is 4x more common than haemophilia B

61
Q

what happens in ITP

A

Autoantibodies develop against GP IIb/IIIA receptor on platelets –> destroyed by spleen –> thrombocytopenia

Happens after infection

It is a type II herpsensitivity reaction

62
Q

Describe the typical presentation of ITP.

A
  • Petechiae (non-blanching rash)
  • Bruises
  • Blood blisters in the mouth - importance for prognosis, more likely to need steroids

diagnosis of exclusion

63
Q

List some differential diagnoses for ITP.

A
  • Henoch-Scholein Purpura
  • Non-accidental injury
  • Coagulation factor defect
  • Inherited thrombocytopaenia
  • Acute leukaemia
64
Q

List some treatment approcahes for ITP.

A
  • Observation (most common)
  • Corticosteroids
  • High dose IVIG
  • IV anti-RhD (if RhD positive)
65
Q

Which type of leukaemia is most common in children?

A

ALL

NOTE: < 1 years old AML is more common than ALL

66
Q

How is hyposplenism managed?

A
  • Vaccination
  • Prophylactic penicillin
  • Advice about other risks (e.g. malaria, dog bites)

YEAR 5: HAEM (20 decks)

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