Paediatric haematology

Question 1

How do paediatric RBCs differ from adult?

Answer 1

Site of haematopoeisis varies

Haemoglobin switching

At birth 55-65% is HbF

Difference in red cell structure and metabolism

Larger red blood cells

Higher haematocrit

Rapidly reach similar values to adults

Question 2

How are WBCs different in children vs adults?

Answer 2

Similar numbers - higher lymphocyte count

IgG crosses the placenta

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

Start producing antibodies at 2-3m

Can make satisfactory immune responses by 6m

Question 3

How do platelets differ in children vs adults?

Answer 3

Reach adult numbers by 18w gestation

Initially larger, by birth slim down to adult size

Functionally different at birth

Hyporesponsive to certain agonists

Hyperresponsive to vWF

Differences balance out

Question 4

How does haemostasis differ in children va adults?

Answer 4

Present but imperfect at birth

Coagulation proteins do not cross placenta effectively

Only fibrinogen, FV(5), FVIII(8), FXIII(13) are normal at birth

Most haemostatic parameters reach adult values by 6 months

Yet, see few problems clinically…unless ill or preterm

Question 5

What is haemmorrhagic disease of the newborn?

Answer 5

The placental gradient means fetal vitamin K is 10% mother

FII(2), FVII(7), FIX(9), FX(10), protein C, protein S are vitamin K dependent

Exacerbated if on anti-convulsants - mother needs oral vitamin K

Warfarin is teratogenic

Question 6

What routine treatment prevents haemmorrhagic disease of the newborn?

Answer 6

Routine neonatal Vit K

Question 7

Which coagulation inhibitors exist at a reduced concentration in neonates?

Answer 7

ATIII

Heparin cofactor 2

TFPI

protein C

protein S

Question 8

Which coagulation proteins exist in unique forms in neonates?

Answer 8

Fibrinogen

Plasminogen

Question 9

Are D dimers and vWF increased or decreased?

Answer 9

Increased

Question 10

What are the possible congenital causes of anaemia in childhood?

Answer 10

Haemoglobin synthesis problem: haemoglobinopathy

Bone marrow failure syndromes

Bone marrow infiltration

Peripheral destruction

Blood loss

Question 11

What versions of Hb exist at the gestational age of 4-14 weeks?

Answer 11

ζ2e2 = Hb Gower-1

ζ2γ2 = Hb Portland

α2e2 = Hb Gower-2

Question 12

What are the possible causes of peripheral destruction?

Answer 12

Rh / ABO or other incompatibility

Membrane defect: hereditary spherocytosis

Enzyme defect: G6PD deficiency, PK deficiency

Infection

Question 13

What is hereditary spererocytosis?

Answer 13

Autosomal dominant abnormality of erythrocytes.

Caused by mutations in genes relating to membrane proteins that allow for the erythrocytes to change shape.

Abnormal erythrocytes are sphere-shaped (spherocytosis).

Dysfunctional membrane proteins interfere with the cell’s ability to be flexible to travel from the arteries to the smaller capillaries.

This difference in shape also makes the red blood cells more prone to rupture

Cells with these dysfunctional proteins are taken for degradation at the spleen. This shortage of erythrocytes results in haemolytic anemia.

Question 14

What might be the cause of acquired childhood anaemia?

Answer 14

Nutritional deficiency: iron, B12, folate

Bone marrow failure

Bone marrow infiltration

Peripheral destruction: haemolysis

Blood loss

Question 15

What are the possible congenital causes of bleeding and bruising in children?

Answer 15

Platelet problem

Clotting factor problem

Connective tissue disorder

Question 16

What are the acquired causes of bleeding and bruising in children?

Answer 16

Trauma: accidental, non-accidental

Tumour

Infection: acute eg meningococcus, chronic eg HIV - Immune disorder: primary - immune thrombocytopenia, TTP, secondary - SLE, ALPS

Bone marrow failure

Drug related