Haemolytic anaemias Flashcards
What are the features of haemolytic anaemia?
1) Increased RBC production
2) Increased RBC breakdown
What does increased RBC production in haemolytic anaemia lead to?
1) Increased reticulocyte count
2) Erythroid hyperplasia
What does increased RBC breakdown in haemolytic anaemia lead to?
1) Increased bilirubin, lactate dehydrogenase (LDH), urobillinogen
2) Reduced haptoglobin level
3) Pigment gallstones
What is hereditary spherocytosis?
Inherited disorder of spectrin.
RBCs lose their membranes during circulation.
Autosomal dominant.
RBCs are spherical.
What is hereditary elliptocytosis?
Weakness of the cytoskeleton of the cell, leading to deformation of the cell.
RBCs are oval or elliptical.
How does glucose-6-phosphate dehydrogenase deficiency (G6PD) causes haemolytic anaemia?
G6PD is only source of NADPH in red cells.
NADPH protects RBCs from oxidative damage.
Typically get anaemia after some form of oxidative stress (EG: Drugs, infection, etc).
Inheritance is sex-linked.
Heterozygosity associated with resistance to
malaria.
Bite cells
How does pyruvate kinase deficiency cause haemolytic anaemia?
Failure to generate ATP so RBCs do not have sufficient quantities of ATP.
Autosomal recessive.
What is the direct coombs test?
Used to identify autoimmune haemolytic anaemias.
It detects antibodies/immunoglobulins attached to RBCs.
Also known as the direct antiglobulin test (DCT).
What is warm auto-immune haemolytic anaemia?
Warm AIHA
Autoimmune haemolytic anaemia is caused by autoantibodies that react with RBCs at temperatures ≥ 37° C
IgG
What is cold auto-immune haemolytic anaemia?
Cold AIHA
Autoimmune haemolytic anaemia that is caused by autoantibodies that react with RBCs at temperatures < 37° C (cold agglutinin disease).
IgM
What is microangiopathic haemolytic anaemia?
Due to mechanical, intravascular haemolysis following pathological changes in small blood vessels.
What is paroxysmal nocturnal
haemoglobinuria?
(PNH)
Acquired disorder of RBC membranes.
Due to mutation within PIG-A gene that leads to inability to produce GPI anchor for membran proteins.
Leads to haemolysis due to lack of complement inhibitors on RBC surface.
What is Ham’s test?
Used to diagnose paroxtsmal nocturnal haemoglobinuria.
The test involves placing red blood cells in mild acid; a positive result is increased RBC fragility.
What are schistocytes? And when can they be seen?
Fragmented part of a red blood cell that are typically irregularly shaped, jagged, and have two pointed ends.
Often seen in patients with haemolytic anaemia.
Other causes include mechanical artificial heart valves and hemolytic uremic syndrome, thrombotic thrombocytopenic purpura.
What are spherocytes? What causes their presentation?
Deep red staining, spherical cells that lack central pallor.
These cells result from loss of cell membrane secondary to partial phagocytosis by macrophages. This is secondary to the presence of antibodies or complement on the surface of red blood cells.
Spherocytes are related to immune mediated haemolytic anaemia.
