Paediatrics - haematology Flashcards
What are the types of haemoglobin present in a healthy adult (2)?
- HbA
- HbA2 (low levels)
What is HbA made up of?
2 alpha, 2 beta chains
What is HbA2 made up of?
2 alpha, 2 delta chains
What is the main Hb present in a foetus?
HbF
What is HbF made up of?
2 alpha, 2 gamma chains
What is the main difference between HbF and HbA in terms of its function?
HbF has a higher affinity to oxygen due to the relatively hypoxic environment of the foetus
What age does HbF usually disappear by?
1 year of age
What happens to the levels of haemoglobin from birth throughout childhood?
Hb at birth is high to compensate for the hypoxic foetal environment (140+), Hb decreases over the first few months/ year of life due to transition to adult Hb (shouldn’t go below 100), Hb increases from that point on up to 130/120
What are 3 categories for the causes of anaemia?
- Haemolysis
- Impaired red blood cell production
- Blood loss
What are the two categories of impaired red cell production in children?
- Red cell aplasia (no RBC production)
- Ineffective erythropoiesis
What causes red cell aplasia (3)?
- Fanconi anaemia
- Parvovirus B19 infection (only in children already with inherited haemolytic anaemias)
- Congenital red cell aplasia
What causes haemolytic anaemia in children (6)?
- Haemaglobinopathies (sickle cell, thalassaemia)
- Hereditary spherocytosis/ eliptocytosis
- G6PD deficiency
- Auto/ allo immune haemolytic
- Infections e.g. malaria
- Mechanical e.g. HUS, TTP (due to turbulent blood flow damaging RBCs)
What are some general features of anaemia in children (4)?
- Failure to thrive
- Pallor
- Fatigue
- Tachycardia/ tachypnoea
What would haemolytic anaemias cause an increase of in the blood?
Bilirubin
What are some features of haemolytic anaemias (3)?
- Jaundice
- Splenomegaly
- Gallstones (due to increased bilirubin excretion)
What causes microcytic anaemia in children (5)?
- Thalassaemia
- Anaemia of chronic disease
- Iron deficiency
- Lead poisoning
- Sideroblastic
What causes normocytic anaemia (5)?
- Aplastic anaemia
- Anaemia of chronic disease
- Acute blood loss
- Haemolytic anaemia
- Hypothyroidism
What are the two categories of macrocytic anaemia?
- Normoblastic
- Megaloblastic
What causes normoblastic macrocytic anaemia (3)?
- Alcohol
- Hypothyroidism
- Liver disease
What causes megaloblastic mactrocytic anaemia (2)?
- B12 deficiency
- Folate deficiency
What is the most common cause of anaemia in children?
IDA
What causes IDA in children (3)?
- Poor intake (not breast fed?)
- Malabsorption
- Blood loss (e.g. ringworm in developing countries)
What is a specific symptom of IDA in children?
PICA (eating non food items)
What is fanconi anaemia?
Inherited impaired response to DNA damage in the bone marrow
How is fanconi syndrome inherited?
Autosomal recessive
What is a complication of fanconi syndrome?
Cancer (esp. AML)
How is hereditary spherocytosis inherited?
Autosomal dominant
What is the pathophysiology of hereditary spherocytosis?
Mutations in the proteins coding for RBC membrane e.g. spectrin
Why does hereditary spherocytosis cause haemolysis?
Spherical shape of RBCs –> destruction in the spleen
What is a complication of hereditary spherocytosis?
Aplastic crisis caused by parvovirus infection
How is hereditary spheocytosis managed (2)?
- Folic acid supplements (due to higher RBC production)
- Splenectomy after age 7
How is hereditary spherocytosis diagnosed?
Blood film (direct Coombs test can exclude AHA)
How does G6PDD cause haemolysis?
Allows ROS to damage and break down RBCs
What can precipitate anaemia in those with G6PDD (2)?
- Certain medications
- Fava (broad) beans
What is sickle cell disease and how is it inherited?
Autosomal recessive condition caused by a mutation in the beta chain on Hb, causing 2 alpha and two mutated beta chains = HbS
How is sickle cell often diagnosed?
In the newborn spot blood test
How does sickle cell disease cause anaemia?
RBCs become sickle shaped especially when stressed –> stuck in blood vessels –> haemolysis
What are some complications of sickle cell disease?
- Sickle cell crises
- Increased infection risk
- Gallstones
- Avascular necrosis
- Stroke
- Priapism (painful erection)
What are the types of sickle cell crises?
- Vaso-occlusive crisis
- Splenic sequestration crisis
- Aplastic crisis
- Acute chest syndrome
What are the symptoms of a Vaso-occlusive crisis in sickle cell disease?
Swollen + painful hand/ foot (or whichever body part is affected)
can be associated with fever
What is splenic sequestration crisis?
RBCs block blood flow in the spleen
What are the signs/ symptoms of splenic sequestration?
- Enlarged painful spleen
- Severe anaemia
- Hypovolaemia (due to blood pooling)
What causes aplastic anaemia in those with sickle cell?
Parvovirus B19
What is acute chest syndrome?
Vessels supplying lungs become clogged with RBCs
What are the signs/ symptoms of acute chest syndrome?
- Fever
- SOB
- Chest pain
- Cough
- Hypoxia
How are sickle cell crises managed?
Supportive management, no specific treatments
How is sickle cell disease managed with medications (2)?
- Hydroxycarbamide (increases production of HbF)
- Crizanlizumab (monoclonal antibody against p-selectin, prevents RBCs from sticking to walls)
What is given as prophylaxis for those with sickle cell?
Penicillin V (stop infections)
Other than pharmacologically, how else is sickle cell managed (4)?
- Blood transfusions
- Vaccinations
- Avoid crises (e.g. prevent dehydration)
- Bone marrow transplant (potentially curative)
How is Thalassaemia inherited?
Autosomal recessive
What is thalassaemia?
Defects in either the alpha or beta Hb chains
What are the different types of alpha thalassaemia?
Ranging in severity from 1 to 4
How does alpha thalassameia compensate for defective Hb?
Produces more HbH (4 beta chains)
What are the different types of beta thalassaemia (3)?
- Thalassaemia minor (1 deleted/ abnormal beta gene)
- Thalassaemia intermedia (2 abnormal/ 1 abnormal 1 deleted beta gene)
- Thalassaemia major (2 deleted beta genes)
What are the signs/ symptoms of thalassaemia?
- Pronounced forehead + malar eminences (chipmunk facies - due to growth of bone marrow)
- Hepatosplenomegally
When is thalassaemia screened for in the UK?
Pregnancy (upon booking appointment)
How is thalassaemia managed (3)?
- Transfusions
- Bone marrow transplant
- Splenectomy
What is a complication of frequent blood transfusions?
Iron overload
How is iron overload treated?
Iron chelation
What age do haemaglobinopathies tend to present?
6 months - 2 years (once HbF decreases in prevalence)