Haem - Paediatric haematology Flashcards
(48 cards)
What predisposes children to nutrient deficiency (and which)
Rapid growth and poor nutrient intake
Iron deficiency, folic acid deficiency
What complications could paediatric haematological disorders lead to
Growth retardation can occur with illness or due to its treatment (i.e. old ALL spinal irradiation treatment)
Pubertal failure / development of 2nd sexual characteristics from illness or treatment (e.g. b-thalassemia major treatment → iron overload )
What are the differences in neonatal blood value ranges compared to adults
Higher:
WCC
Neutrophils
Lymphocytes
Hb
MCV
+ higher HbF %
What are the causes of polycythaemia in the foetus
Twin-to-twin transfusion
Intrauterine hypoxia (foetus responds by increased EPO)
Placental insufficiency
What are the causes of anaemia in the foetus
Twin-to-twin or Foetal-to-maternal (rare) transfusion
Parvovirus infection B19 (virus not cleared by immature immune system)
Haemorrhage from cord or placenta
How are foetal RBC enzymes different to adults’ enzymes
~50% the G6PD concentration of an adult
What are the causes of haematological damage in the foetus
Irradiation
Damage by something crossing the placenta (e.g. drugs, chemicals, antibodies)
Anticoagulants (→ haemorrhage or foetal deformity (e.g. vitamin K if given in the first trimester))
Antibodies can destroy red cells, white cells or platelets
Substances in breast milk (e.g. G6PDD-baby may suffer from haemolysis if mother eats fava beans)
Describe the association between Down’s syndrome and leukaemia
Down’s syndrome is associated with congenital leukaemia (transient abnormal myelopoiesis)
○ This is different from leukaemia in older children (TAM is a myeloid leukaemia)
○ This disease tends to remit spontaneously within the first 2 months of life
○ However, it tends to relapse 1-2 years later in about 25% of infants
○ The capacity for spontaneous remission is similar to neuroblastoma
What are haemoglobinopathies
structurally abnormal Hb
Define thalassaemia
Group of genetic disorders characterised by a defect in and reduced globin chain synthesis
What are the differences in the timing globin chain synthesis
alpha globin synthesis begins early in foetal life
beta globin synthesis begins late in gestation
Describe the beta cluster in globin synthesis
Chromosome 11: beta, delta, gamma, epsilon (embyronic)
Deletion of the locus control region B (LCRB) → reduced globin expression
Describe the alpha cluster in globin synthesis
Chromosome 16: alpha 1, alpha 2, zeta (embryonic)
Deletion of locus control region A (LCRA) → reduced globin expression
Describe haemoglobin A and when it is present
𝛼2β2
Late foetus, infant, child, adult
Describe haemoglobin A2 and when it is present
𝛼2δ2
Infant, child, adult (<3.5%)
Describe haemoglobin F and when is it present
𝛼2γ2
Foetus and infant
Describe haemoglobin in utero
Specific foetal haemoglobins are present in the first 16 weeks → HbF predominates
After around 32 weeks you get a rapid increase in HbA production
At birth, about 1/3rd of haemoglobin is HbA, but this rapidly increases after birth
HbA2 production is much slower and starts from birth
What is the pathophysiology of sickle cell disease
Usually RBCs elongate to pass through the capillary beds to post-capillary venules
(1) Hypoxia → polymerisation of haemoglobin S → crescent shaped RBCs and blocked blood vessels (usually reversible when hypoxia is resolved)
(2) If circulation slows, the cells sickle and become rigid and adherent to the endothelium which causes obstruction
(3) Retrograde capillary obstruction → arterial obstruction
What are the types of sickle cell disease
ββS / AS: Sickle cell trait (not sickle cell disease)
βSβS / SS: Sickle cell anaemia
βC / SC: Sickle cell / haemoglobin C disease (Compound - Sickling slightly milder than HbSS)
βSβThal: Sickle cell / beta thalassaemia (Compound)
What does severity of compound sickle cell (βSβThal) depend on
whether it is a:
Beta-0 gene (no beta globin production)
Beta+ gene (a little bit of beta globin production)
At what time does sickle cell anaemia and beta thalassaemia start to clinically manifest and why
3-6 months of life
Gamma chain production and HbF synthesis DECREASE
HbS , HbA production INCREASE
What are the symptoms of sickle cell anaemia in children
Hand-foot syndrome (swelling) (red bone marrow extends into the digits)
Splenomegaly
Acute splenic sequestration
Acute chest syndrome
Painful crises (40%)
Stroke(4-8%)
Hyposplenism
Bacteraemia
What are the types of bone marrow
Yellow BM is largely fat
Red BM produces haematopoietic precursors with developing RBCs and white cell and is vascular, metabolically active and requires an oxygen supply, so it is susceptible to infarction
What is the difference between adult and child splenic complications of sickle cell anaemia
Adult / older-child spleen – spleen is small and fibrotic from recurrent infarction
Suffer from more chance of sequalae of hyposplenism (i.e. pneumococcal infection)
Child spleen – still has a functioning spleen
Children can undergo splenic sequestration which is the acute pooling of a large percentage of circulating red cells in the spleen → SEVERE ANAEMIA, SHOCK and DEATH
