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8. CP - Core Haematology > (42) Paediatric haematology > Flashcards

(42) Paediatric haematology Flashcards

(67 cards)

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1
Q

The site of haematopoesis varies between children and adults. Explain the differences

A
  • embryos = yolk sac

- then spleen, liver, lymph nodes - bone marrow takes over and forms most RBCs when it develops

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2
Q

Haematopoesis occurs in the bone marrow in both children and adults but what are the differences?

A

children = marrow of long bones eg. femur and tibia

adults = mainly in pelvis, cranium, vertebrae and sternum

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3
Q

How much of haemoglobin is HbF at birth?

A

55-65%

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4
Q

What are the differences in red blood cells between children and adults?

A

In children:

  • larger
  • higher haematocrit
  • greater oxygen affinity

Rapidly reach similar values to adults

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5
Q

What is haematocrit?

A

Also known as packed cell volume (PCV) or erythrocyte volume fraction (EVF), is the volume percentage (%) of red blood cells in blood. It is normally 45% for men and 40% for women

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6
Q

Which chromosome is responsible for the production of 2 alpha chains?

A

Chromosome 16

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7
Q

Which chromosome is responsible for the production of 2 beta chains?

A

Chromosome 11

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8
Q

Which chromosome is responsible for the production of gamma chains and delta chains?

A

Chromosome 11

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9
Q

What haemoglobin switching occurs to form alpha chains? (chromosome 16)

A

zeta - alpha

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10
Q

What haemoglobin switching occurs to form delta chains? (chromosome 11)

A

epsilon - gamma - beta - delta

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11
Q

What types of haemoglobin exist between weeks 4-14 of gestation?

A 
2zeta/2epsilon = Hb Gower-1
2zeta/2gamma = Hb Portland
2alpha/2epsilon = Hb Gower-2
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12
Q

What type of haemoglobin exists after week 14 of gestation?

A

2alpha/2gamma = HbF

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13
Q

What types of haemoglobin exist at the neonatal stage?

A 
2alpha/2beta = HbA
2alpha/2delta = HbA2
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14
Q

What globin chains is Hb Portland made up of?

A

2zeta/2gamma

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15
Q

What globin chains is HbA2 made up of?

A

2alpha/2delta

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16
Q

What globin chains is Hb Gower-2 made up of?

A

2alpha/2epsilon

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17
Q

What globin chains is HbF made up of?

A

2alpha/2gamma

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18
Q

What globin chains is HbA made up of?

A

2alpha/2beta

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19
Q

What globin chains is Hb Gower-1 made up of?

A

2zeta/2epsilon

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20
Q

How does the number of white blood cells differ in children from adults?

A

Similar numbers - higher lymphocyte counts

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21
Q

The immune system is a work in progress. Describe how the immune system is built up in a child

A
  • IgG crosses the placenta
  • IgA/D/E/G/M in breast milk (passive immunity)
  • start producing own antibodies 2-3 months
  • can make satisfactory immune response by 6 months
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22
Q

Which antibodies cross the placenta?

A

IgG

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23
Q

How else do babies receive passive immunity from the mother?

A

Breast milk (antibodies IgA, IgD, IgE, IgG, IgM)

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24
Q

At what age do babies start producing their own antibodies?

A

2-3 months

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25
At what age are babies able to make a satisfactory immune response?
6 months
26
When do platelets levels reach that of an adult?
By week 18 out of 40 of gestation
27
How are platelets different in the foetus?
Initially larger, but slim down to adult size by birth
28
Platelets are functionally different at birth. In what way?
- hyporesponsive to certain agonists | - hyperresponsive to vWF
29
What is haemostasis?
The human body's response to blood vessel injury and bleeding. It involves a coordinated effort between platelets and numerous blood clotting proteins (or factors), resulting in the formation of a blood clot and subsequent stopping of the bleed
30
Is haemostasis present at birth?
Present but imperfect at birth | - coagulation proteins do not cross the placenta effectively
31
Which coagulation proteins are normal at birth?
- fibrinogen - FV - FVIII - FXIII only these are normal at birth
32
Most haemostatic parameters reach adult values by what age?
6 months
33
Which (anti)coagulation factors are vitamin K dependent?
- FII - FVII - FIX - FX - protein C - protein S
34
Foetal vitamin K is what proportion mother?
The placental gradient means that foetal vitamin K is 10% mother
35
What is the function of vitamin K in the body?
Required for complete synthesis of certain proteins that are prerequisites for blood coagulation (needed for normal blood clotting)
36
What is prevented by giving routine neonatal vitamin K?
Haemorrhagic disease of the newborn
37
The risk of vitamin K-deficient haemorrhagic disease of the newborn is increased in what circumstances?
If the mother is on anti-convulsants - the mother needs to take oral vitamin K
38
Name a drug that is teratogenic
Warfarin
39
In the neonate, pro-coagulant proteins are reduced such as...
FII, FVII, FIX, FXI, FXII, prekallikrein, high molecular weight kininogens
40
In the neonate, there is a reduced concentration of coagulation inhibitors, such as...
- ATIII - Heparin - cofactor 2 - TFPI - protein C - protein S
41
The neonate has unique forms of which proteins?
- fibrinogen | - plasminogen
42
The neonate has raised levels of what? (concerning haemostasis)
- D dimers | - vWF
43
What are the congenital causes of anaemia in children?
- haemoglobin synthesis problem (HAEMOGLOBINOPATHY) - bone marrow failure syndromes - bone marrow infiltration - PERIPHERAL DESTRUCTION - BLOOD LOSS
44
What proportion of the worldwide population carry an abnormal gene causing haemoglobinopathy?
5%
45
How many babies are born per year with a type of haemoglobinopathy?
300,000
46
Name 2 types of haemoglobinopathy
- thalassaemia | - sickle cell disease
47
Where are haemoglobinopathies most common geographically?
Middle of Africa (malaria protection)
48
Describe 4 things that can cause peripheral destruction of red blood cells?
- an incompatibility - membrane defect - enzyme defect - infection
49
Give 2 types of incompatibility that can cause RBC peripheral destruction?
- Rh | - ABO
50
What is Rh incompatibility?
A condition that occurs during pregnancy if a woman has Rh-negative blood and her baby has Rh-positive blood
51
ABO incompatibility is more common than Rh incompatibility but why is it rarely a significant problem?
As IgM antibodies cannot cross the placenta
52
Name a type of RBC membrane defect that can cause peripheral destruction
Hereditary spherocytosis
53
What is hereditary spherocytosis?
- autosomal dominant abnormality of RBC membrane proteins - abnormal erythrocytes are sphere-shaped - more prone to rupture - cells with these dysfunctional proteins are taken for degradation at the spleen = anaemia and jaundice
54
Give 2 clinical features seen in hereditary spherocytosis?
- anaemia | - jaundice (due to breaking down of red blood cells)
55
Give 2 types of enzyme defects that cause peripheral destruction of RBCs
- G6PD deficiency | - PK deficiency
56
Another cause of anaemia in babies is blood loss. Give 2 causes of blood loss in babies
- twin to twin transfusion (one baby bleeding into the other) - fetomaternal haemorrhage (loss of foetal blood cells into maternal circulation)
57
What are the acquired causes of anaemia in childhood?
- NUTRITIONAL DEFICIENCY - BONE MARROW FAILURE - BONE MARROW INFILTRATION - peripheral destruction - blood loss
58
What nutritional deficiencies cause acquired anaemia in childhood?
- IRON - B12 - folate
59
Do we have larger stores of B12 or folate?
B12
60
Give an example of a disease of bone marrow failure
Aplastic anaemia
61
What is aplastic anaemia?
A rare disease in which the bone marrow and the hematopoietic stem cells that reside there are damaged (bone marrow failure) - this causes pancytopenia - aplastic refers to inability of the stem cells to generate mature blood cells
62
Is aplastic anaemia a serious condition?
Serious and difficult to manage - child will need bone marrow transplant
63
Give an example of a disease of bone marrow infiltration?
ALL leukaemia (signs = pale, frequent nosebleeds etc.)
64
What are the congenital causes of bleeding and bruising in children?
- platelet problem (most common) - clotting factor problem - connective tissue disorder (more rare)
65
What are the acquired causes of bleeding and bruising in children?
- trauma - tumour - infection - immune disorder - bone marrow failure - drug related
66
Give examples of infections that can cause bleeding and bruising in children
- meningococcus | - chronic eg. HIV
67
Give examples of immune disorders that can cause bleeding and bruising in children
``` primary = immune thrombocytopenia, TTP secondary = SLE, ALPS ```

8. CP - Core Haematology (11 decks)

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