haemolytic anaemias Flashcards
Define hemolytic anaemia.
Anemia caused by shortened red cell survival
- List some examples of extra-vascular haemolysis.
Autoimmune h aemolytic an aemia
Hereditary spherocytosis
- List some examples of intra-vascular haemolysis.
Malaria G6PD deficiencv Pyruvate kinase deficiency Mismatched blood transfusion MAHA Paroxysmal nocturnal haemoglobinuria
- What is the most common cause of intravascular haemolysis worldwide?
Malaria
- 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 hemolytic 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 hemolytic anemia have an increased risk of developing gallstones?
Increased generation of bilirubin
- Co-inheritance of which condition with HA could further increase the risk of gallstones?
Gilbert’s syndrome
- Describe the genetic cause of Gilbert’s syndrome.
Caused by the UGT TA7/TA7 genotype
This means that in stead 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
- The red cell lipid membrane rests on a cytoskeleton. What is this cytoskeleton made up of?
Spectrin