Haemolysis Flashcards
What is haemolysis?
Premature RBC destruction
What makes RBCs susceptible to damage?
Biconcave shape
Lack of mitochondria
Lack of nucleus
Can haemolysis be compensated for?
Yes by bone marrow up-regulation.
Only works for a certain degree of haemolysis.
What are the consequences of excess haemolysis?
Erythroid hyperplasia
Excess RBC breakdown products
How does the bone marrow respond to haemolysis?
Reticulocytosis
In the more chronic cases, there will be erythroid hyperplasia.
What is the biggest source of cell production in adults?
Iliac crests
What are the 2 types of haemolysis?
Extravascular (most common)
Intravascular
Where are cells destroyed in extravascular haemolysis?
Usually in the spleen/liver.
Where are cells destroyed in intravascular haemolysis?
Usually within the circulation.
How does extravascular haemolysis present?
Splenomegaly +/- hepatomegaly
Jaundice
Gallstones
Bilirubinuria
What form of bilirubin is produced from the breakdown of RBCs?
Unconjugated bilirubin
How does intravascular haemolysis present?
Pink urine (due to haemoglobinuria)
Upon blood testing there will be haemoglobinuria and methaemalbuminaemia
Urine may also contain haemosiderins
Which form of haemolysis is a potentially life-threatening presentation?
Intravascular haemolysis
What is a key difference between extravascular and intravascular haemolysis?
In extravascular haemolysis, products are normal but present in excess.
In intravascular haemolysis, abnormal products are formed.
What are the 3 causes of intravascular haemolysis?
ABO incompatibility
G6PD deficiency
Severe falciparum malaria
All other causes of haemolysis produce the extravascular form.
What is haptoglobin?
A serum protein that binds free haemoglobin.
This is reduced/undetectable if free haemoglobin is present - as it all becomes bound.
What is autoimmune haemolysis?
The development of IgG or IgM against RBCs.
It is usually of idiopathic origin.
What is alloimmune haemolysis?
The presence of IgM which causes immediate intravascular haemolysis and IgG which causes delayed extravascular haemolysis.
Can occur in haemolytic transfusion reactions and haemolytic disease of the newborn.
What are causes of mechanical cell destruction?
DIC HUS TTP Leaking heart valves Infection
What is the issue in those with membrane defects?
There is reduced membrane deformability, with increased transit time through the spleen, making these cells more likely to undergo extravascular haemolysis.
What can cause RBC membrane defects?
Liver disease
Vitamin E deficiency
Hereditary spherocytosis
Paroxysmal nocturnal haemoglobinuria
What is the role of G6PD?
Provides antioxidants to protect cell.
Provides ATP for an energy source.
What 2 therapies can cause normal cells to undergo oxidative stress?
Dapsone
Salazopyrin
