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CP reviewer 1 > Paediatric Haematology > Flashcards

Paediatric Haematology Flashcards

1
Q

Describe how the site of haematopoiesis varies from foetus –> child

A

early foetus –> yolk sac

late foetus –> liver and spleen

neonate and child –> bone marrow

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2
Q

What haemoglobin switch occurs at birth?

A

A shift from γ-globin to β-globin gene expression around birth –> switch from foetal (α2γ2; HbF) to adult (α2β2; HbA) Hb production

  • 55-65% is HbF at birth
  • By 6 months of age the major Hb is HbA
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3
Q

Define haematocrit

A

The ratio of the volume of red blood cells to the total volume of blood.

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4
Q

On which chromosome are alpha chains produced?

A

16

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5
Q

On which chromosome are beta, gamma and delta chains produced?

A

11

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6
Q

What is Hb Portland 1?

A

Hb Portland is a form of Hb existing at low levels during embryonic and foetal life, composed of two zeta chains and two gamma chains.

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7
Q

What are the the human embryonic haemoglobins?

A

Hb Gower 1
Hb Gower 2
Hb Portland 1
Hb Portland 2

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8
Q

What are the 2 types of adult Hb?

A

HbA –> 2 alpha 2 beta

HbA2 –> 2 alpha 2 delta

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9
Q

Describe the difference between the affinity of Hb for O2 in foetus vs adult

A

HbF has a stronger affinity for O2 compared to HbA

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10
Q

What is P50?

A

p50 is the oxygen tension when hemoglobin is 50 % saturated with oxygen.

A lower p50 means stronger binding or higher affinity for oxygen.

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11
Q

What are reticulocytes?

A

Reticulocytes are immature red blood cells (RBCs)

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12
Q

What Ig crosses the placenta to give the foetus passive immunity?

A

IgG

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13
Q

What Ig are present in breast milk?

A

Breast milk has IgA, IgD, IgE, IgM

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14
Q

When do children start producing antibodies?

A

Children start producing antibodies at 2-3 months, and can make a satisfactory immune response by 6 months

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15
Q

When are vaccinations carried out? Why?

A

Vaccinations are carried out at 2-3 months as they are very vulnerable and can carry out a good enough response

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16
Q

When do platelets reach adult numbers?

A

18w gestation

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17
Q

How are platelets functionally different at birth?

A

o Hypo-responsive to certain agonists
o Hyper-responsive to vWF
o Differences balance out

18
Q

Do coagulation factors cross the placenta? Why?

A

Not effectively, so the foetus will not get any from the mother.

This is important because it reduces likelihood of clots forming within the placenta.

19
Q

What coagulation factors are present at birth?

A

Only fibrinogen, Factors 5, 8, 13 are normal at birth (remember as 5+8=13), most other parameters reach adult values by 6 months

20
Q

Which form of haemophilia is it possible to detect at birth?

Why?

A

It is possible to detect Haemophilia A at birth but not B (only 8 is present, not 9)

21
Q

Which coagulation factors are vitamin K dependent?

A 
o	Factor 2
o	Factor 7
o	Factor 9
o	Factor 10
o	Protein C
o	Protein S
22
Q

foetal vitamin K is 10% that of the mother due to..?

A

Placental gradient

23
Q

What is haemorrhagic disease of the newborn (HDN)?

A

Vitamin K deficiency-related bleeding - a rare disease with high mortality and morbidity

24
Q

Why are newborns offered a vitamin K injection?

A

To prevent HDN

25
Q

Which class of drug has been thought to exacerbate vitamin K deficiency in neonates?

A

AEDs (anti-convulsants)

26
Q

Why is warfarin teratogenic?

A

Warfarin is teratogenic as it inhibits vitamin K (stands for Wisconsin animal research farm), was used as rat poison to make them bleed

27
Q

Potential causes of congenital anaemia?

A
  • Haemoglobin synthesis problem: haemoglobinopathy
  • Bone marrow failure syndromes
  • Bone marrow infiltration
  • Peripheral destruction
  • Blood loss
28
Q

Where is the mutation present in sickle cell disease?

A

single gene mutation on Beta chain causes sickling, sticky cells.

29
Q

What is Rh incompatibility?

A

A condition that occurs during pregnancy if a woman has Rh-negative blood and her baby has Rh-positive blood. Rh factor is a protein on red blood cells.

30
Q

What is hereditary spherocytosis?

A

An abnormality of RBCs. The disorder is caused by mutations in genes relating to membrane proteins that allow for the erythrocytes to change shape

Normal biconcave RBCs are spherical instead and rupture easily. No central pallor seen as the RBCs are spherical and thus not thinner in the centre.

31
Q

What 2 enzyme deficiencies can lead to peripheral destruction of RBCs?

A 
o	G6PD deficiency
o	PK (pyruvate kinase) deficiency
32
Q

What is a G6PD deficiency?

A

G6PD helps red blood cells work. It also protects them from substances in the blood that could harm them.

G6PD deficiency is a genetic disorder that most often affects males.

33
Q

What is PK (pyruvate kinase) deficiency?

A

Without pyruvate kinase, red blood cells break down too easily, resulting in low levels of these cells (haemolytic anaemia).

34
Q

What is twin to twin transfusion?

A
  • Only occurs in monochorionic twin foetuses which share a placenta. The blood circulation becomes shared due to connecting blood vessels within the placenta, allowing blood to pass from one twin to the other
  • One twin confers RBCs to the other, due to disproportionate blood vessel growth or direction.
  • The redder twin has too many RBCs, and will need plasma transfusions to dilute the RBCs

Fetomaternal haemorrhage – usually not a problem due to high platelets

35
Q

What is the most common cause of acquired childhood anaemia?

A

Iron deficiency

36
Q

What nutritional deficiencies can lead to acquired childhood anaemia?

A

iron (most common), B12, folate

37
Q

How can bone marrow failure lead to acquired childhood anaemia?

A

normal stem cells do not make much blood

38
Q

How can bone marrow infiltration lead to acquired childhood anaemia?

A

malignancy takes over function and space of bone marrow, storage disorders

39
Q

Congenital causes of bruising and bleeding?

A

o Platelet problem (inherited)
o Clotting factor problem
o Connective tissue disorder

40
Q

Acquried causes of bruising and bleeding?

A

o Trauma: accidental, non-accidental (without good clotting, children are vulnerable)
o Tumour
o Infection: acute e.g. meningococcus, chronic e.g. HIV
o Immune disorder: (primary – immune thrombocytopenia (TTP), secondary – SLE, ALPS
o Bone marrow failure
o Drug related

CP reviewer 1 (59 decks)

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