Red blood cells Flashcards
What is anaemia?
Reduction in red cell count or haemoglobin content of red cell count
What are general aetiologies to anaemia?
Bloof loss
Decreased production
Defective production
Increased destruction
What is a reticulocyte?
Immature red blood cell - not fully haemoglobinised
What metals are required for blood production?
Iron
Copper
Cobalt
Manganese
What vitamins are required for red cell production?
B12 Folic acid Thiamine B6 C E
What hormones are required to produce red cells?
Erythropoietin
GM-CSF
Androgens
Thyroxine
What is a normal red cell lifespan?
120 days
Where does red cell breakdown occur?
Spleen
What are red cells broken down to?
Globin - amino acids
Haem - iron - recycled into haemoglobin, haem - billirubin
What happens to billirubin after red cell breakdown?
Binds to albumin in the plasma
Where can genetic effects cause congenital anaemia?
Red cell membrane
Metabolic pathways - enzymes
In haemoglobin
What maintains the shape of red cells?
Skeletal proteins in the membrane
What is the commonest red cell membrane disorder?
Hereditary spherocytosis
Is hereditary spherocytosis autosomal dominant or recessive?
Dominant
What is clinical presentation of congenital anaemias?
Anaemia
Jaundice (neonatal)
Spenomegaly
Pigment gallstones
How do we treat hereditary spherocytosis?
Folic acid
Transfusion
Spenectomy if severe anaemia
What are rarer membrane disorders?
Hereditary elliptocytosis
Hereditary pyropoikilocytosis
South east asian ovalocytosis
What pathways are important in red cells?
Glycolytic pathway
Pentose phosphate shunt
What is the purpose of the pentose phosphate shunt?
Protection from oxidative damage
What enzymes can be affected in red cells leading to anaemia?
Glucose-6-phosphate dehydrogenase
Pyruvate kinase
What happens to the cell in the absence of glucose-6-phosphate dehydrogenase?
Cell is vulnerable to oxidative damage
Why is G6PD deficiency common in malarial areas?
Provides protection from malaria
How does G6PD deficiency present?
Variable degrees of anaemia
Neonatal jaundice
Splenomegaly
Pigment gallstones
Does illness affect red cell production?
Yes
What are triggers to haemolysis in G6PD deficiency?
Infection
Acute illness
Broad beans
Drugs
What shifts the oxygen dissociation curve to the left?
Decrease pH
Increase in 2,3-diphosphoglycerate
Increase in temperature
How many alpha and beta chains are in haemoglobin?
2 alpha
2 beta
What happens to haemoglobin in the first year of life?
It is shifted from foetal haemoglobin to haemoglobin A by switching off gamma chains and switching on beta chains
What is haemoglobinopathy?
Abnormality of haemoglobin synthesis
What is reduced or absent globin chain prouction called?
Thalassaemia alpha or beta depending which chain is affected
What is sickle cell disease?
Point mutation of the beta globin chain
Is sickle cell disease autosomal recessive or dominant?
Recessive
What will be seen under the microscope in a patient with sickle cell?
Some normal cells
Some sickle cells
When do red cells sickle?
After deoxygenation
What happens to blood vessels in sickle cell patients?
Vaso-occlusion
What happens after haemolysis in sickle cell?
Endothelial activation
Promotion of inflammation
Coagulation activation
Dysregulation of vasomotor tone by vasodilator mediatiors
What are systemic presentations of sickle cell?
Chest crisis
Stroke
Hyposplenism
Gallstones
How is sickle cell managed?
Life long prophylaxis:
Vaccination
Penicillin and malarial prophylaxis
Folic acid
How is acute event of sickle cell managed?
Hydration Oxygenation Prompt treatment of infection Analgesia Blood transfusion
What are clinical features of beta thalassaemia major?
Severe anaemia Present at 3-6 months of age Expansion of ineffective marrow Bony deformities Splenomegaly Growth retardation
What is life expectancy for untreated beta thalassaemia major?
<10 years
What are different types of thalassaemia?
Homozygous alpha zero thalassaemia
Beta thalassaemia major
Non-transfusion dependent thalassaemia
Thalassasaemia minor
How is beta thalassaemia major treated?
Chronic transfusion 4-6 weekly
Watch for iron overload - will kill if untreated
Iron chelated - iron excreted
What drugs can be used for iron chelation therapy?
Desferal
Exjade
