Paediatric Haematology

Question 1

What are the 4 main things to remember when treating a child as opposed to an adult?

Answer 1

1) May weigh more or less than 70kg
2) Congenital conditions are more relevant
3) Everything is moving
4) Children exist within a family - management often involved siblings, parents etc.

Question 2

What are the 6 differences between child and adults RBCs?

Answer 2

1) Child site of haematopoiesis varies
2) Hb switching occurs
3) At birth 55-65% of Hb is HbF
4) Difference in red cell structure and metabolism
5) Larger red blood cells in children
6) Children have a higher haematocrit

Question 3

What are the sites of haematopoiesis in children?

Answer 3

In embryo - yolk sac then liver and spleen

Bone marrow takes over but if this is insufficient liver and spleen can be re-recruited to help

Question 4

What is Hb switching?

Answer 4

Chr 16 can produced zeta or alpha chains
Chr 11 can produce epslon, gamma, beta and delta chains
Different types of Hb composed of different chain combos are produced at different periods of gestation

Question 5

What different Hbs are produced between 4-14 weeks of gestation due to Hb switching?

Answer 5

Hb Gower-1 = 2 zeta, 2 epslon
Hb Portland = 2 zeta, 2 gamma
Hb Gower-2 = 2 alpha, 2 epslon

Question 6

What type of Hb is produced >14 weeks of gestation til birth due to Hb switching?

Answer 6

HbF = alpha 2 gamma 2

Question 7

What 2 types of Hb are produced in the neonatal stage?

Answer 7

HbA = alpha 2 beta 2

HbA 2 = alpha 2 delta 2

Question 8

How do child WBC counts differ to adult?

Answer 8

Similar numbers but children have higher lymphocyte counts

Question 9

What type of Ig can cross the placenta, why is this physiologically appropriate?

Answer 9

IgG (IgM cannot)

IgG confers wider protection, whereas IgM would only confer protection against stuff you were currently exposed to

Question 10

What is an important source of passive immunity in neonates?

Answer 10

Breast milk - has IgA, IgD, IgE, IgG, IgM

Question 11

At how many months do children start producing there own Ab?

Answer 11

2-3 months

Question 12

After how many months can children mount a satisfactory immune response?

Answer 12

6 months

Question 13

At how many months are immunisations given?

Answer 13

2 months, with boosters
Although child cannot mount a satisfactory immune response at this point without vaccination until 6 months there would be a lot of neonatal deaths, vaccination at 2 months provides just enough protection

Question 14

Which type of blood cell reaches adult levels first and why?

Answer 14

Platelets - reach adult leaves by week 18 of gestation

Birth is a bloody process, coagulation is very important

Question 15

In what 3 ways do platelets at birth differ to adult platelets?

Answer 15

1) Initially larger but by birth slim down to adult size
Functionally different at birth:
2) Hyporesponsive to certain agonists
3) Hyperresponsive to vWF

Question 16

For what 3 reasons is haemostasis although present at birth not perfect?

Answer 16

1) Coagulation proteins do not cross the placenta effectively
2) Only fibrinogen, FV, FVIII and FXIII are normal at birth
3) Most haemostatic parameters reach adult values by 6 months

Question 17

Few bleeding problems are seen clinically despite imperfect haemostasis, in which 2 situations may they occur?

Answer 17

1) Pre term babies

2) Ill babies

Question 18

Which 6 coagulation factors are Vit K dependent?

Answer 18

1) FII (thrombin)
2) FVII
3) FIX
4) FX
5) Protein C
6) Protein S

Question 19

Why are neonates Vit K deficient and thus require IM vit K?

Answer 19

Because the placental gradient means fetal Vit K in 10% of mother

Question 20

What condition is prevented by routine neonatal Vit K?

Answer 20

Haemorrhagic disease of the newborn

Question 21

Why should warfarin be avoided in pregnancy?

Answer 21

Its teratogenic

Question 22

In what situation is Vit K deficiency of the newborn exacerbated and therefore mother requires oral Vit K?

Answer 22

If mother is on anti convulsants

Question 23

What are the 5 key things about neonatal haemostasis?

Answer 23

1) Pro-coagulant factors reduced, 2,7, 9,,11,12, pre kallikrein, high molecular weight kininogens
2) Reduced concentration of coagulation inhibitors: ATIII, heparin co factor 2, TFPI, Protein C, Protein S
3) Unique forms of fibrinogen and plasminogen
4) Raised D dimers and vWF
5) Platelet aggregation differs

Question 24

What are the 5 congenital causes of anaemia in childhood?

Answer 24

1) Hb synthesis problem: haemoglobinopathy (sickle cell of thalassemia)
2) Bone marrow failure syndromes
3) Bone marrow infiltration
4) Peripheral destruction - making RBCs but they are being destroyed
5) Blood loss

Question 25

Give the 4 causes of peripheral destruction of RBCs leading to anaemia in childhood?

Answer 25

1) Rh/ABO or other incompatibility
2) Membrane defect: hereditary spherocytosis
3) Enzyme defect: G6PD deficiency, PK deficiency
4) Infection

Question 26

Why is peripheral destruction of RBCs particularly relevant in new born?

Answer 26

Haematopoesis stops for about 10 weeks post birth - RBCs that are being destroyed are not replaced

Question 27

ABO incompatibility is more common than Rh incompatibility, why does Rh cause more problems clinically?

Answer 27

Mother ABO IgM cannot cross the placenta

Childs ABO Ag not presented on RBCs til after birth

Question 28

Give 2 causes of blood loss leading to congenital anemia?

Answer 28

1) Twin to twin transfusion: can be shocking, one twin large and red, the other small and white
2) Fetomaternal haemorrhage

Question 29

What is the main cause of acquired childhood anaemia?

Answer 29

Iron deficiency

Question 30

Give the 5 causes of acquired childhood anaemia?

Answer 30

1) Nutritional deficiency: iron, B12, folate
2) Bone marrow failure
3) Bone marrow infiltration
4) Peripheral destruction: haemolysis
5) Blood loss

Question 31

What are the 3 congenital causes of bleeding and bruising in the neonate?

Answer 31

1) Platelet problem
2) clotting factor problem
3) Connective tissue disorder

Question 32

What are the 6 acquired causes of bleeding and bruising in the neonate?

Answer 32

1) Trauma: both accidental and non accidental
2) Tumour
3) Infection: acute eg. meningococcus, chronic eg. HIV
4) Immune disorder: primary - immune thrombocytopenia, TTP, secondary SLE and ALPS
5) Bone marrow failure
6) Drug related