Haematology 2 - Paediatric haematology Flashcards
(43 cards)
How does WCC, neutrophils, lymphocytes, Hb and MCV compare in neonates to adults?
all higher in neonates
why don’t disorders of beta globin genes manifest in neonates?
Neonates - ↑ HbF → disorders of beta globin genes less likely to manifest
What are some causes of polycythaemiain the foetus?
Twin-to-twin transfusion
Intrauterine hypoxia
Placental insufficiency
What are some causes of anaemia in the foetus?
Twin-to-twin or Foetal-to-maternal (rare) transfusion
Parvovirus infection (virus not cleared by immature immune system)
Haemorrhage from cord or placenta
what other condition is congenital leukaemia associated with?
Down syndrome (AKA: transient abnormal myelopoiesis / TAM)
different from leukaemia in older children (TAM is myeloid leukaemia)
remit spontaneously within first 2 months of life (similar to neuroblastoma)
relapse 1-2 years later in about 25% of infants
How should congenital leukaemia in Down’s syndrome be managed?
It will resolve spontaneously so it’s okay
define thalassaemia
↓ synthesis globin chain(s) - defects in globin gene
Describe the strucure of Hb
4 globin chains
HbA - 2 alpha and 2 beta globin chains
Where are the globin genes located?
chromosome 11 (beta cluster - beta gamma, delta) and 16 (alpha 1 and 2)
locus control region required for synthesis of all chains (deletion of LCRB → reduced downstream globin expression:)
why do defects in the synthesis of a and b globin chains present at different times?
alpha globin synthesis begins early in foetal life whereas beta globin synthesis begins late in gestation
Which Hb form is predomninant in utero and at birth?
HbF predominates 16wks
32 weeks→ rapid increase in HbA production
At birth, about 1/3rd of haemoglobin is HbA, but this rapidly increases after birth
recall the pathophysiology of sickle cell disease
Hypoxia → polymerisation of Hb S → crescent RBCs → blocked blood vessels
reversible if hypoxic state is resolved (unless very sickled)
Where does vascular occlusion in sickle cell anaemia usually occur?
post-capillary venules (when passing through these venules, red cells tend to elongate)
circulation slows → cells sickle → adherent to endothelium → obstruction
Retrograde capillary obstruction → arterial obstruction
Why may there be Howel-Jolly bodies on the blood film in sickle cell disease?
They are produced when there is splenic infarction - hyposplenism
(nucleated RBCs)
How is sickle cell disease diagnosed at birth?
Guthrie spot test
If not identified in a Guthrie spot, at what age does sickle cell disease tend to present?
around 6 months of age as…
Gamma chain production and HbF synthesis DECREASE
HbS production INCREASE
In what age group might the hand-foot syndrome of sickle cell disease present?
<2 years
Adult haematopoietic BM = axial skeleton
Child haematopoietic BM = axial skeleton + bones of hands and feet →hand-foot syndrome (swollen hands and feet due to infarction of underlying bone)
what are some vaso-occlusive disease in sickle cell disease?
Hand-foot syndrome tends to occur in the first 2 years of life
Acute chest syndrome is caused by infarction in ribs and lungs
Sickle cell anemia = one of the MOST COMMON causes of stroke in childhood
How does the spleen differ in adults and children in sickle cell disease and what are the implications of this?
Adult / older-child spleen
- spleen small and fibrotic from recurrent infarction
- suffer from sequalae of hyposplenism (i.e. pneumococcal infection)
Child spleen
- still functioning spleen
- splenic sequestration possible -acute pooling → SEVERE ANAEMIA, SHOCK and DEATH
- Parents taught how to palpate spleen and to seek medical attention if needed
- Blood transfusion required
Why is there no risk of splenic sequestration in sickle cell disease once Howel-Jolly bodies have been identified on blood film?
Once there has been a splenic infarction (which will cause Howel Jolly bodies) you will get hyposplenism but there is no risk of sequestration
When are you most susceptible to bacteraemia in sickle cell disease?
younger ages irrespective of hyposplenism
Children particularly vulnerable to pneumococcus and parvovirus (immature immune system)
Pneumococcal infection FATAL in SCA - prevented with vaccination and penicillin
what are the consequence of parvovirus infection in sickle cell disease?
aplastic anaemia
shortened RBC lifespan - acute severe anaemia
Why is there an increased folic acid demand in sickle cell?
Hyperplastic erythropoiesis
Growth spurts
Red cell lifespan is shorted so anaemia can rapidly worsen
In sickle cell disease, when is the highest risk of stroke?
In childhood (actually less common in adults with sickle cell)
