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YEAR 5: Haematology PM > Haem: Paediatric haematology > Flashcards

Haem: Paediatric haematology Flashcards

1
Q

Which feature of children predisposes them to nutrient deficiencies?

A

Rapid growth

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2
Q

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

A
  • Higher WCC (neutrophils, lymphocytes)
  • Higher Hb
  • Higher MCV
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3
Q

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

A

They have 50% of the concentration of G6PD of adults

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4
Q

List some causes of polycythaemia in a foetus.

A
  • Twin-to-twin transfusion syndrome (recepient twin)
  • Intrauterine hypoxia
  • Placental insufficiency
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5
Q

List some causes of anaemia in a foetus.

A
  • Twin-to-twin transfusion syndrome (donor twin)
  • Foetal-to-maternal transfusion (foetomaternal haemorrhage)
  • Parvovirus infection
  • Bleeding from cord or placenta
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6
Q

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

A

In utero

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7
Q

What is transient abnormal myelopoiesis (TAM) and what congential condition is assoicated with?

A
  • congenital leukaemia
  • The presence of preleukaemic blasts in the bone marrow and blood of a neonate
  • 20% of these children will develop myeloid leukaemia within 4 years
  • Associated with Down’s syndrome
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8
Q

What lineage is the myeloid leukaemia associated with TAM?

A

Megakaryocyte

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9
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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10
Q

Define haemoglobinopathy.

A

Conditions characterised by synthesis of structurally abnormal haemoglobin.

NOTE: thalassemias are sometimes considered a form of haemoglobinopathy

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11
Q

On which chromosomes are the different globin genes expressed?

A

Beta chain - chromosome 11

  • Beta
  • Delta
  • Gamma
  • Epsilon

Alpha chain - chromosome 16

  • Alpha 1 and 2
  • Zeta
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12
Q

What is the globin chain composition of 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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13
Q

What is the normal HbA2 level in a healthy adult?

A

< 3.5%

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14
Q

Which foetal haemoglobins are present in the first 16 weeks?

A
  • Gower 1 (2 zeta, 2 epsilon)
  • Gower 2 (2 alpha, 2 epsilon)
  • Portland 1 (2 zeta, 2 gamma)
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15
Q

Describe how the different haemoglobin levels in utero and in the first year of life change.

A
  • Haemoglobin Gower 1 and 2 and Portland are present in the first 16 weeks
  • HbF predominates throughout most of foetal life and is present until 9 months postpartum
  • HbA slowly starts around 2 weeks. After 32 weeks, there is a rapid increase in production
  • HbA2 starts being synthesised at 28 weeks
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16
Q

What are the proportions of HbA and HbF at birth?

A

1/3 HbA
2/3 HbF

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17
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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18
Q

Outline the pathophysiology of sickle cell anaemia (specifically mechanims of sickling)

A
  • Hypoxia induces HbS polymerisation and subsequent sickling of RBC
  • RBCs become more adeherent to the endothelium and lead vessel occlusion
  • This tends to occur in the post-capillary venule
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19
Q

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

A

Howell-Jolly bodies - clusters of DNA (pathognomic of splenic dysfunction)

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20
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
  4. HbS/beta thalassemia - severity depends on thalassaemia beta chain expression
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21
Q

When is sickle cell anaemia usually diagnosed in the UK?

A

At birth following the Guthrie test

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22
Q

At what age does sickle cell disease present and why?

A
  • Presents at 5 months
  • Clinical features only manifest when HbF levels drop and HbS levels increase
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23
Q

Why do symptoms of 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
  • Bone pain due to infarction is a prominent clinical feature in sickle cell anaemia

Hence this is why hand-foot syndrome only occurs in young children

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24
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 axial skeleton
  • Infants/Children - can happen anywhere (particular in hands and feet)
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25
Q

What age group does hand-foot syndrome affect?

A

<2 years

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26
Q

What is splenic sequestion?

A

Vaso-occlusion in the spleen leading to acute pooling of blood in the spleen leading to hypovolaemia, shock and death

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27
Q

Why does splenic sequestion only occur in children and not older patients?

A
  • As patients with SCD age, numerous splenic infarcts lead to hyposplenism and a small and fibrotic spleen
  • Children typically still have function spleens
28
Q

How is splenic sequestration managed?

A
  • Blood transfusion
  • Splenectomy

Parents should be taught how to palpate the spleen and to seek help when the child is acutely unwell with a large spleen

29
Q

What does hyposplenism increase the risk of? How is this managed?

A
  • Infection by encapuslated bacteria
  • Prevented with vaccinations and prophylactic antibiotics
30
Q

Which infectious agents are particularly dangerous in children with SCD?

A
  • Pneumococcus
  • Parvovirus B19
31
Q

What can parvovrius B19 cause in SCD?

A

Aplastic anaemia

32
Q

How can pneumococcal infection be prevented in a patient with sickle cell anaemia?

A
  • Vaccination
  • Prophylactic antibiotics
33
Q

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

A

Reduced red cell lifespan

34
Q

What are the principles of managing sickle cell anaemia in children?

A
  • Monitoring with swift recognition and treatment of complications
  • Educate parents
  • Vaccinations
  • Antibiotic prophylaxis
  • Folic acid
35
Q

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

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

NOTE: there is an moderate form of the disease called beta-thalassaemia intermedia

36
Q

List some clinical features of beta thalassaemia major.

A
  • Anaemia → heart failure, growth retardation
  • Erythropoietic drive → bone expansion, hepatomegaly, splenomegaly
  • Iron overload → heart failure, gonadal failure
37
Q

What are the principles of treatment of beta thalassaemia major?

A
  • Accurate diagnosis and family counselling
  • Blood transfusion
  • Iron chelation therapy
  • Consider child as individual an part of family
38
Q

Name an iron-chelating drug

A

Desferrioxamine

39
Q

List some types of inherited haemolytic anaemia.

A
  • Red cell membrane - hereditary spherocytosis, hereditary eliptocytosis
  • Haemoglobin molecule - sickle cell anaemia, thalassaemia
  • Glycolytic pathway - pyruvate kinase deficiency
  • Pentose shunt - G6PD deficiency
40
Q

Give an example of acquired congential haemolytic anaemia

A

Haemolytic disease of the newborn

41
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?
42
Q

What type of anaemia would also cause a low reticulocyte count?

A

Aplastic

43
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 synthesis
44
Q

List some triggers for haemolysis in G6PD deficiency.

A
  • Infections
  • Drugs
  • Naphthalene
  • Fava beans
45
Q

What is the inheritance pattern of G6PD deficiency?

A

X-linked recessive

46
Q

What 2 signs would be seen on the blood film of someone with G6PD deficiency?

A
47
Q

What are the two important types of acquired haemolytic anaemia in children?

A
  • Autoimmune haemolytic anaemia
  • Haemolytic uraemic syndrome
48
Q

How is AIHA diagnosed?

A
  • Positive DAT
  • Spherocytes on blood film
49
Q

What is the HUS triad?

A
  • Acute renal failure
  • Microangiopathic haemolytic anaemia
  • Thrombocytopenia
50
Q

What is microangiopathic haemolytic anaemia?

A

Intravascular haemolysis of occuring due excessive shear forces in small vessels

51
Q

What can be seen on blood film that is pathognomic of MAHA?

A

Schisocytes

52
Q

What are the most common inherited defects of coagulation?

A
  • Haemophilia A
  • Haemophilia B
  • Von Willebrand disease
53
Q

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

A
  • Haemarthrosis when starting to walk
  • Bruises
  • Excessive post-traumatic or surgery bleeding
54
Q

List some differential diagnoses for haemophilia.

A
  • Inherited thrombocytopaenia/platelet defect
  • Acquired defects of clotting (e.g. ITP, acute leukaemia)
  • Non-accidental injury
  • Henoch-Schonlein purpura
55
Q

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

A
  • History and examination
  • Family history
  • Coagulation screen (APTT, PT, fibrinogen)
  • Platelet count (rules out platelet causes)
  • Assays for specific coagulation factors
56
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
57
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
58
Q

Describe the typical presentation of von Willebrand disease.

A
  • Mucosal bleeding
  • Bruises
  • Post-traumatic bleeding
59
Q

Why do von Willebrand disease and haemophilia A present similarly?

A

They are both characterised by low level of factor 8

60
Q

How is von Willebrand disease diagnosed?

A
  • Family history (mainly autosomal dominant)
  • Coagulation screen
  • vWF antigen assay
  • Factor 8 assay
  • (Bleeding time)
  • Platelet aggregation studies
61
Q

How is von Willebrand disease treated?

A
  • Desmopressin (stimulates vWF release from endothelium)
  • Factor VIII or vWF replacement
62
Q

Describe the relative prevalence of haemophilia A and B.

A

Haemophilia A is 4x more common than haemophilia B

63
Q

Describe the typical presentation of ITP.

A
  • Petechiae
  • Bruises
  • Bleeding from mucous membranes

Typically post-infection

64
Q

List some differential diagnoses for ITP.

A
  • Henoch-Scholein Purpura
  • Non-accidental injury
  • Coagulation factor defect
  • Inherited thrombocytopaenia
  • Acute leukaemia
65
Q

How is ITP diagnosed?

A
  • History
  • FBC and blood film (low platelets with normal to large platelets on film)
  • Coagulation screen (normal)
  • Bone marrow biopsy (rarely)
66
Q

List some treatment approaches for ITP.

A
  • Observation (most common)
  • Corticosteroids
  • High dose IVIG
  • IV anti-RhD (if RhD positive)
67
Q

Which type of leukaemia is most common in children?

A

ALL

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

YEAR 5: Haematology PM (18 decks)

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