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YR5 Haematology > Paediatric Haematology > Flashcards

Paediatric Haematology Flashcards

1
Q

What are causes of polycythaemia in fetuses and neonates?

A

Twin-to-twin transfusion

Intrauterine hypoxia (increased EPO synth)

Placental insufficiency (leads to IU hypoxia)

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2
Q

What are unique causes of anaemia in fetuses and neonates?

A

Twin-to-twin transfusion

Fetal-to-maternal transfusion

Parvovirus infection (virus not cleared by immature immune system)

Haemorrhage from the cord or placenta

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3
Q

What is the type of congenital leukaemia associated with Down’s Syndrome?

A

Specific type of neonatal leukaemia (AKA. transient abnormal myelopoiesis or TAM) differs greatly from leukaemia in older infants or children.

Often remits spontaneously

May relapse 1-2y

Myeloid with major involvement of megakaryocytic lineage

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4
Q

Newborn babies, in contrast to adults, have:

A. A higher Hb

B. A lower WBC

C. Smaller red blood cells

D. The same percentage of haemoglobin F

A

A. A higher Hb

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5
Q

Which globin chains are haemoglobin A made of and when is it present?

A

α2 β2

Late fetus, infant, child + adult

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6
Q

Which globin chains are haemoglobin A2 made of and when is it prevelant?

A

α2 δ2

Infant, child + adult

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7
Q

Which globin chains are haemoglobin F made of and when is it prevalent?

A

α2 γ2

Fetus + infant

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8
Q

Why does sickle cell anaemia not manifest at birth?

A

Clinical features manifest as gamma chain production + HbF synthesis decrease

+

βS + HbS production increase.

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9
Q

Why does sickle cell anaemia present differently in infants and children compared to adults?

A
  1. Distribution of red BM (susceptible to infarction) differs: “Hand-foot” syndrome- spreads into limbs + digits
  2. Infant still has a functioning spleen—splenic sequestration can occur.
  3. Infant has immature immune system, no immunity to pneumococcus + parvovirus
  4. Infant growing rapidly with greater need for folic acid
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10
Q

What is splenic sequestration?

A

Acute pooling of a large % of circulating red cells in the spleen.

Spleen enlarges acutely.

Hb falls acutely + death can occur.

Doesn’t happen in older children + adults because recurrent infarction has left the spleen small + fibrotic

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11
Q

Why does folic acid matter more in a child with sickle cell disease than in a normal child or an adult?

A

Hyperplastic erythropoiesis requires folic acid.

Growth spurts require folic acid.

Red cell life span is shorter so anaemia can rapidly worsen.

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12
Q

Complications of sickle cell anaemia that are more common in adults than children include:

A. Hand-foot syndrome

B. Hyposplenism

C. Red cell aplasia

D. Splenic sequestration

E. Stroke

A

B. Hyposplenism

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13
Q

Siblings with sickle cell anaemia present simultaneously with severe anaemia and a low reticulocyte count—likely diagnosis?

A. Splenic sequestration

B. Parvovirus B19 infection

C. Folic acid deficiency

D. Haemolytic crisis

E. Vitamin B12 deficiency

A

B. Parvovirus B19 infection

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14
Q

A 6-year-old Afro-Caribbean boy presents with chest and abdominal pain; Hb is 63 g/l, MCV 85 fl and blood film shows sickle cells—likely diagnosis?

A. Sickle cell trait

B. Sickle cell anaemia

C. Sickle cell/beta thalassaemia

A

B. Sickle cell anaemia

MCV is normal

If C would have microcytosis

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15
Q

What can inherited haemolytic anaemias be due to?

A

Defects in:

  • Red cell membrane
  • Haemoglobin molecule
  • Red cell enzymes: glycolytic pathway
  • Red cell enzymes: pentose shunt
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16
Q

What are the principles of diagnosis of haemolytic anaemias?

A

Is there anaemia?

Is there evidence of increased red cell breakdown, e.g. jaundice, splenomegaly, increased unconjugated bilirubin?

Is there evidence of increased red cell production, e.g. increased reticulocyte count, bone expansion?

Are there abnormal red cells?

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17
Q

A 1-year-old boy presents with joint bleeding, Hb, WBC and platelet count are normal, aPTT is prolonged, PT is normal, bleeding time normal—most likely diagnosis?

A. Haemophilia A

B. Haemophilia B

C. Von Willebrand disease

D. Thrombotic thrombocytopenia purpura

E. Has taken mother’s warfarin tablets

A

A. Haemophilia A

A is more common than B

Bleeding time would be normal in VWD

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18
Q

What is the presentation of (auto)-immune thrombocytopaenic pupura?

A

Petechiae

Bruises

Blood blisters in mouth

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19
Q

What are ddx for autoimmune thrombocytopaenic purpura?

A

Henoch‒Schönlein purpura

Non-accidental injury

Coagulation factor defect

Inherited thrombocytopenia

Acute leukaemia

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20
Q

What does rapid growth in childhood predispose to?

A

Vitamin + mineral deficiency

e.g. Iron + Folic acid

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21
Q

How do kids and adults generally differ in immune response to infections?

A

Kids: Lymphocytosis

Adults: Neutrophilia

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22
Q

What lymphocytes are common in kids? Why?

A

Reactive lymphocytes

Frequent encounters with new microbial antigens

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23
Q

How does neonate blood composition differ to adults?

A

Highest % HbF than any other point: so disorders of B global genes less likely to manifest

G6PD conc. ~50% higher than in adults

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24
Q

What is the fetal circulation susceptible to?

A

Irradiation or something crossing from the mother into their circulation: drugs, chemicals, antibodies

Anticoagulants: Haemorrhage / Fetal deformity

Antibodies: destroy RBC, WBC, platelets (fathers antigens)

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25
Q

Give an example where breast milk can damage the neonatal blood supply

A

Lactating woman eating fava beans

G6PD deficient son may suffer haemolysis

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26
Q

When does the first mutation subsequently leading to childhood leukaemia often occur?

A

In uteru

Pre-leukaemic cells carrying this mutation can spread from one twin to another

27
Q

What is a haemoglobinopathy?

A

Genetic disorder with synthesis of a structurally abnormal globin chain molecule

May also refer to any inherited disorder of globin chain synthesis

28
Q

What is thalassaemia?

A

Genetic disorder with reduced globin chain synthesis

29
Q

Describe the presence of haemoglobin in foetal life/ neonates

A

HbF dominates

HbA rises slightly, then steeply after birth

HbA2 rises later nearer birth, then gradually

30
Q

What is sickle cell disease?

A

Group of chronic conditions with sickling of RBCs caused by inheritance of haemoglobin S (HbS)

31
Q

Describe the pathophysiology of sickling cells

A
  1. Hypoxia
  2. HbS polymerises when deoxygenated, causing sickling of RBCs
  3. Sickling makes RBC’s more fragile + inflexible- obstruction occurs
  4. Retrograde capillary obstruction- thrombosis
32
Q

What is the genotype in Sickle Cell trait? How does this present?

A

HbAS
Asymptomatic except in conditions that favour sickling (hypoxia, dehydration)

33
Q

What is Sickle Cell Anaemia?

A

Homozygosity for HbS
βSβS

34
Q

What causes formation of HbS?

A

Point mutation in β globin gene (2α + 2β globin chains form HbA)

Valine subs glutamic acid on position 6= non-polar so insoluble

35
Q

What is sickle haemoglobin C disease?

A

Compound heterozygous state

βS + βC

36
Q

What is sickle cell beta thalassaemia?

A

Compound heterozygous state

βS + βThal

β0 with no synth of β chain from that gene, have only βS

OR

β+: some HbA produced, but less than normal

37
Q

What test is used to detect sickle cell disorders at birth?

A

Guthrie spot

38
Q

Describe the ages at which children are at differing risk of vaso-occlusion in the first decade

A
  1. Hand-foot syndrome: <2y
  2. Acute chest syndrome: 3y = peak + plateau
  3. Painful crises: high throughout
  4. Stroke: more in <10s than adults due to narrow cerebral vessels
39
Q

What happens as the risk of splenic sequestration decreases?

A

Risk of hyposplenism increases

Becomes smaller + fibrotic

Spleen important in immunity

Filters out bacteria + parasites

Source of antibody production

40
Q

What does first exposure to parvovirus B19 in children with sickle cell disease lead to?

A

Pure red cell aplasia

Arrests maturation of developing red cells in BM
With such reduced lifespan of RBC’s in SCD, results in dramatic fall in Hb

Requires transfusion

41
Q

What does folic acid matter more in a child with sickle cell disease than in a normal child or adult?

A

Hyperplastic erythropoiesis requires folic acid

Growth spurts require folic acid

Red cell lifespan is shorter so megaloblastic anaemia can develop + rapidly worsen

42
Q

Give 4 key components to management of sickle cell disease in the infant + child

A

Accurate dx

Educate parents

Vaccinate: pneumococcal + meningococcal

Prescribe folic acid + penicillin

43
Q

What causes beta thalassaemia and when would it first manifest?

A

Reduced synth of beta globin chain + therefore HbA

First 3-6m

But can perform Guthrie spot at birth

44
Q

Describe the prognosis of beta thaleassaemia heterozygosity/ trait

A

Harmless

Important genetically if both parents have the trait

β thal β

45
Q

What is the genotype in homozygous beta thalassaemia? What is the prognosis?

A

β thal β thal

Severe anaemia, in absence of blood transfusion is fatal in first few years

46
Q

What are the clinical effects of poorly treated thalassaemia major?

A

Anaemia: HF, growth retardation

Increased erythropoietic drive: bone expansion + extra medullary haematopoesis in liver + spleen

Iron overload: HF, gonadal failure

47
Q

Describe management of beta thalassaemia major in children

A

Accurate dx + family counselling

Blood transfusion

Chelation therapy once iron overload starts to occur: Desferiozamine

48
Q

What can cause a non inherited congenital haemolytic anaemia?

A

Transplacental passage of antibodies cause haemolytic disease of the newborn

e.g. RhD +ve neonate, mother with anti-D

49
Q

Name 2 red cell membrane defects that can lead to haemolytic anaemia in children

A

Hereditary spherocytosis

Hereditary elliptocytosis

50
Q

Name a haemoglobin defect that can lead to haemolytic anaemia in children

A

Sickle cell anaemia

51
Q

Name a glycolytic pathway defect that can lead to haemolytic anaemia in children

A

Pyruvate kinase deficiency

(Rare)

52
Q

Name a pentose shunt defect that can lead to haemolytic anaemia in children

A

G6PD deficiency

53
Q

What is autoimmune haemolytic anaemia characterised by?

A

Spherocytosis

+ve direct antiglobulin test (Coombs’)

54
Q

What is haemolytic uraemic syndrome?

A

thrombotic microangiopathy in which microthrombi, consisting primarily of platelets, form + occlude arterioles + capillaries.

55
Q

What triad of pathologies arise in HUS? What symptoms do these give rise to?

A

Thrombocytopenia: petechiae, purpura, mucosal bleeding, prolonged bleeding after minor cuts
MAHA: fatigue, dyspnea, pallor, jaundice
AKI: haematuria, proteinuria, oliguria, anuria

56
Q

What is found on the blood film in HUS?

A

Small angular fragments + microspherocytes (Schistocytes)

57
Q

What is the most common cause of HUS?

A

EHEC O157:H7 E Coli infection
Usually transmitted via contaminated foods (e.g. undercooked beef or raw leafy vegetables)

58
Q

List the 3 most common inherited defects of coagulation

A

Haemophilia A

Haemophilia B

Von Willebrand disease

59
Q

Give 4 ways in which haemophilia A + B may initially present

A

Bleeding following circumcision

Haemarthroses when starting to walk

Bruises

Post-traumatic bleeding

60
Q

Give 4 differentials to haemophilia

A

Inherited thrombocytopenia or platelet function defect

Acquired defects of coagulation e.g. ITP, acute leukaemia

Non-accidental injury

Henoch‒Schönlein purpura

61
Q

Give 3 features of Von Willebrand disease presentation. What is the pathophysiology? What differential may you consider?

A

Mucosal bleeding

Bruises

Post-traumatic bleeding

Defect in platelet function + lack of factor 8

Haemophilia A: factor 8 also reduced

62
Q

What is the treatment of Von Willebrands disease?

A

Lower purity factor 8 concentrates

63
Q

What is the treatment of ITP?

A

Observation

Corticosteroids

High dose IV immunoglobulin

IV anti-RhD (if Rh+ve)

64
Q

Describe the prevalence of acute leukaemia in children

A

ALL most common

AML occurs at all ages, + in <1s is more common than ALL

YR5 Haematology (20 decks)

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