Haemolytic anaemia Flashcards
what are the 2 main presentations of haemolytic anaemia?
scleral icterus
pale conjuctiva and skin
describe the blood tests for haemolytic anaemia?
Hb low
Haptoglobin low
Unconjugated bilirubin raised
LDH raised
what are the 2 general mechanisms of haemolytic anaemia?
intravascular and extravascular
what is intravascular haemolysis?
Intravascular is typically something shearing or attacking the RBCs causing cell lysis and leakage of cellular components.
what is haptoglobin?
Haptoglobin is your blood’s mop for free haemoglobin. When cells lyse it mops up the exposed Hb and as a result Haptoglobin is used up (lowers). This happens exclusively in intravascular haemolysis
What is extravascular haemolysis?
Extravascular haemolysis mainly occurs in the spleen, as errors in RBCs cause the spleen to lyse and remove RBCs from circulation.
what are the 3 classes of hereditary haemolytic anaemias?
Membrane- hereditary spherocytosis
Enzymes- G6PD deficiency
Haemoglobin- sickle cell and thalassaemia
What are the affects of a G6PD deficiency?
G-6-PD leaves a person vulnerable to oxidative stress. The enzyme is involved in the hexose monophosphate shunt pathway. This pathway essentially allows you to restock NADPH which in turn helps maintain glutathione levels. Glutathione is protective in oxidative stress – its normalises the free radicals present in reactive oxidative species.
inheritance of G6PD?
x linked recessive
what are the classic oxidative stressors in G6PD?
Fava beans, naphthalene moth ball, antimalarials
what can be seen on blood film in G6PD?
Heinz bodies- visible intracellular inclusions of denatured haemoglobin. They are detected via specific stains. They are present during haemolytic anaemia due to oxidative damage. Bite cells- result of the spleen removing the denatured haemoglobin inclusions (the Heinz bodies).
what is the inheritance of hereditary spherocytosis and describe its epidemiology?
autosomal dominant
white nothern european
outline the pathophysiology of HS?
in beta spectrin or ankyrin leads to a weak cytoskeleton. This cytoskeleton cannot maintain the biconvex disc shape of the RBC and so it pops out into a spherical shape
What is the investigation for hereditary spheroctyosis?
The osmotic fragility test is actually coming out of clinical practice now as it is quite laborious. It involves giving a patient hypotonic saline. This acts as a stressor because it alters the membrane potential around the RBC. HS cells are more prone to lyse in response to this stressor.
what is an aplastic crises and why is it common is HS patients?
Aplastic crisis- fail to produce red cells (just red cells). I
more common in HS patients due to Parvovirus B19 infection.
HS cells only live around 30 days because their shape leaves them vulnerable to damage in the microcirculation.
The body relies heavily on the BM to compensate with increased production. Parvovirus invades RBC precursors in the BM and prevents this
These patients are predisposed to a resultant aplastic crisis compared to the normal population who are infected due to their reduced RBC life spans.
