Haemolytic Anaemias Flashcards
(36 cards)
- Define haemolytic anaemia.
Anaemia caused by shortened red cell survival
- List some examples of extra-vascular haemolysis.
Autoimmune haemolytic anaemia
Hereditary spherocytosis
- List some examples of intra-vascular haemolysis.
Malaria G6PD deficiency Pyruvate kinase deficiency Mismatched blood transfusion MAHA Paroxysmal nocturnal haemoglobinuria
- What is paroxysmal nocturnal haemoglobinuria caused by?
An acquired defect in the GPI anchor which is one of two mechanisms by which cells attach proteins to their surface
- List some consequences of haemolytic anaemia.
Anaemia Erythroid hyperplasia Increased folate demand Susceptibility to parvovirus B19 infection Propensity to gallstones Increased risk of iron overload Increased risk of osteoporosis
- Why is parvovirus B19 infection dangerous in patients with haemolytic anaemia?
It infects erythroid cells in the bone marrow and arrests their maturation
If this happens in someone with shortened red cell survival, it can cause a dramatic drop in Hb (aplastic crisis)
NOTE: this can be identified by observing a low reticulocyte count
- Why do people with haemolytic anaemia have an increased risk of developing gallstones?
- Co-inheritance of which condition could further increase the risk of gallstones?
Increased generation of bilirubin
Gilberts
- Describe the genetic cause of Gilbert’s syndrome.
Caused by the UGT TA7/TA7 genotype
This means that instead of the usual 6 TA repeats, there is an extra dinucleotide on each allele which is associated with reduced transcription of UGT 1A1 and, consequently, reduced production of enzyme in the liver and less efficient bilirubin conjugation
- Why is there an increased risk of iron overload with haemolytic anaemia?
Increased intestinal iron absorption (also due to transfusions)
- List some clinical features of haemolytic anaemia.
Pallor Jaundice Splenomegaly Family history Pigmenturia
- List some laboratory features of haemolytic anaemia.
Anaemia Increased reticulocytes Polychromasia Increased LDH Increased bilirubin Reduced/absent haptoglobins Haemoglobinuria Haemosiderinuria
- What is polychromasia?
Red cells take up both eosinophilic and basophilic dye giving them a bluish appearance – this is due to the presence of reticulocytes
- What is increased LDH a marker of?
LDH is an enzyme found in high concentrations within red cells
Increased LDH suggests intravascular haemolysis
- What are haptoglobins? What is the significance of reduced haptoglobins?
Haptoglobins are proteins in the bloodstream that bind to and remove free haemoglobin from the bloodstream
Low haptoglobins suggests that there is a lot of free haemoglobin in the bloodstream
- Which stains are used for haemosiderinaemia?
Perl’s stain
Prussian blue stain
- What does the presence of haemoglobinuria and haemosiderinaemia imply?
Intravascular haemolysis
- What is the hall mark of red cells in hereditary spherocytosis?
Osmotic fragility – red cells show increases sensitivity to lysis in hypotonic saline
- Describe the appearance of the blood film in hereditary spherocytosis.
The cells lack a central area of pallor because they have lost the biconcave shape
The cells are small and more densely stained
There may be polychromatic cells (due to the presence of a young red cell population)
- Outline the blood film and FBC features of eliptocytosis.
The red cells are elliptical but there is no polychromasia and the blood count is likely to be normal because there is little haemolysis
- Describe the appearance of the blood film in eliptocytosis.
Fragmentation of red cells and a lot of variation in the shape of red cells (poikilocytosis)
It can cause severe haemolytic anaemia
- Describe the inheritance pattern of G6PD deficiency.
X-linked recessive
- Outline the importance of G6PD in the red cell.
G6PD catalyses the first step in the pentose phosphate pathway
This reaction generates NADPH which is required to maintain intracellular glutathione
Glutathione protects red cells against oxidative stress
A lack of G6PD, means that red cells are at increased risk of oxidative damage
list the possible clinical effects of G6PD deficiency.
Neonatal jaundice
Acute haemolysis
Chronic haemolytic anaemia (rare)
- List some triggers for haemolysis in G6PD deficiency.
Drugs (antimalarials, antibiotics, dapsone, vitamin K)
Infections
Fava beans
Naphthalene mothballs
