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YEAR 5: Haematology PM (COPY) > Haem: Paediatric haematology > Flashcards

Haem: Paediatric haematology Flashcards

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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
What age group does hand-foot syndrome affect?
<2 years
26
What is splenic sequestion?
Vaso-occlusion in the spleen leading to acute pooling of blood in the spleen leading to hypovolaemia, shock and death
27
Why does splenic sequestion only occur in children and not older patients?
- As patients with SCD age, numerous splenic infarcts lead to hyposplenism and a small and fibrotic spleen - Children typically still have function spleens
28
How is splenic sequestration managed?
* Blood transfusion * Splenectomy ## Footnote Parents should be taught how to palpate the spleen and to seek help when the child is acutely unwell with a large spleen
29
What does hyposplenism increase the risk of? How is this managed?
- Infection by encapuslated bacteria - Prevented with vaccinations and prophylactic antibiotics
30
Which infectious agents are particularly dangerous in children with SCD?
* Pneumococcus * Parvovirus B19
31
What can parvovrius B19 cause in SCD?
Aplastic anaemia
32
How can pneumococcal infection be prevented in a patient with sickle cell anaemia?
* Vaccination * Prophylactic antibiotics
33
Why do children with sickle cell anaemia have increased folate demands?
Reduced red cell lifespan
34
What are the principles of managing sickle cell anaemia in children?
* Monitoring with swift recognition and treatment of complications * Educate parents * Vaccinations * Antibiotic prophylaxis * Folic acid
35
Describe the difference in severity of beta thalassaemia trait and beta thalassaemia major.
* 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
List some clinical features of beta thalassaemia major.
* Anaemia → heart failure, growth retardation * Erythropoietic drive → bone expansion, hepatomegaly, splenomegaly * Iron overload → heart failure, gonadal failure
37
What are the principles of treatment of beta thalassaemia major?
* Accurate diagnosis and family counselling * Blood transfusion * Iron chelation therapy * Consider child as individual an part of family
38
Name an iron-chelating drug
Desferrioxamine
39
List some types of inherited haemolytic anaemia.
* **Red cell membrane** - hereditary spherocytosis, hereditary eliptocytosis * **Haemoglobin molecule** - sickle cell anaemia, thalassaemia * **Glycolytic pathway -** pyruvate kinase deficiency * **Pentose shunt** - G6PD deficiency
40
Give an example of acquired congential haemolytic anaemia
Haemolytic disease of the newborn
41
What should you look for when investigating a patient with suspected haemolytic anaemia?
* 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
What type of anaemia would also cause a low reticulocyte count?
Aplastic
43
Aside from the haemolysis, what else contributes to anaemia in sickle cell anaemia?
* HbS has a low affinity for oxygen meaning that is releases oxygen readily to tissues * This reduces EPO synthesis
44
List some triggers for haemolysis in G6PD deficiency.
* Infections * Drugs * Naphthalene * Fava beans
45
What is the inheritance pattern of G6PD deficiency?
X-linked recessive
46
What 2 signs would be seen on the blood film of someone with G6PD deficiency?
47
What are the two important types of acquired haemolytic anaemia in children?
* Autoimmune haemolytic anaemia * Haemolytic uraemic syndrome
48
How is AIHA diagnosed?
- Positive DAT - Spherocytes on blood film
49
What is the HUS triad?
- Acute renal failure - Microangiopathic haemolytic anaemia - Thrombocytopenia
50
What is microangiopathic haemolytic anaemia?
Intravascular haemolysis of occuring due excessive shear forces in small vessels
51
What can be seen on blood film that is pathognomic of MAHA?
Schisocytes
52
What are the most common inherited defects of coagulation?
* Haemophilia A * Haemophilia B * Von Willebrand disease
53
Describe the typical presentation of haemophilia A and B in an infant.
* **Haemarthrosis** when starting to walk * Bruises * Excessive post-traumatic or surgery bleeding
54
List some differential diagnoses for haemophilia.
* Inherited thrombocytopaenia/platelet defect * Acquired defects of clotting (e.g. ITP, acute leukaemia) * Non-accidental injury * Henoch-Schonlein purpura
55
What are some key aspects of investigating a child with a suspected defect of coagulation?
* History and examination * Family history * Coagulation screen (APTT, PT, fibrinogen) * Platelet count (rules out platelet causes) * Assays for specific coagulation factors
56
List some specific details of an infant's early history that could be suggestive of a disorder of coagulation.
* Bleeding from the umbilical cord * Bleeding after the Guthrie test * Haematoma formation after vitamin K injection/vaccines * Bleeding after circumcision
57
What are the principles of treatment of inherited disorders of coagulation?
* Counselling the family * Treatment of bleeding episodes * Use of prophylactic coagulation factors
58
Describe the typical presentation of von Willebrand disease.
* Mucosal bleeding * Bruises * Post-traumatic bleeding
59
Why do von Willebrand disease and haemophilia A present similarly?
They are both characterised by low level of factor 8
60
How is von Willebrand disease diagnosed?
* Family history (mainly autosomal dominant) * Coagulation screen * vWF antigen assay * Factor 8 assay * (Bleeding time) * Platelet aggregation studies
61
How is von Willebrand disease treated?
- Desmopressin (stimulates vWF release from endothelium) - Factor VIII or vWF replacement
62
Describe the relative prevalence of haemophilia A and B.
Haemophilia A is 4x more common than haemophilia B
63
Describe the typical presentation of ITP.
* Petechiae * Bruises * Bleeding from mucous membranes Typically post-infection
64
List some differential diagnoses for ITP.
* Henoch-Scholein Purpura * Non-accidental injury * Coagulation factor defect * Inherited thrombocytopaenia * Acute leukaemia
65
How is ITP diagnosed?
- History - FBC and blood film (low platelets with normal to large platelets on film) - Coagulation screen (normal) - Bone marrow biopsy (rarely)
66
List some treatment approaches for ITP.
* Observation (most common) * Corticosteroids * High dose IVIG * IV anti-RhD (if RhD positive)
67
Which type of leukaemia is most common in children?
ALL NOTE: \< 1 years old AML is more common than ALL

YEAR 5: Haematology PM (COPY) (18 decks)

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