Haemolysis Flashcards
what is haemolysis?
the premature destruction of red cells
what is compensated haemolysis?
increased red cell destruction that is compensated for by increased red cell producction
what happens to the Hb level in compensated haemolysis?
it is maintained so the patient won’t become anaemic
what is another name for haemolytic anaemia?
decompensated haemolysis
what is haemolytic anaemia?
increased rate of red cell destruction that exceeds the bone marrows capacity for red cell production
causes a fall in Hb
what are the two main consequences of haemolysis?
erythroid hyperplasia
excess RBC breakdown products
what is erythroid hyperplasia?
increased bone marrow RBC production
the appropriate response to reduced RBC levels
what is the appropriate bone marrow response to haemolysis and how is this achieved?
increase RBC production
via reticulocytosis and erythroid hyperplasia
what are the two types of haemolysis based on where the haemolysis occcurs?
extravascular
intravascular
what happens in extravascular haemolysis?
RBCs are taken up by the reticuloendothelial system - mainly the spleen and liver
what type of haemolysis is more common - intra or extra vascular?
extravascular
what organ changes can be seen in extravascular haemolysis?
splenomegaly
hepatomegaly
what is RBC product is released in extravascular haemolysis?
protoporphyrin
what findings would be seen in extravascular haemolysis?
unconjugated bilirubinaemia
urobilinogenuria
what are two possible consequences of high bilirubin levels in extravascular haemolysis?
jaundice
gallstones
what happens in intravascular haemolysis?
red cells are destroyed within the circulation, causing their contents to spill into the blood
what four findings are seen in intravascular haemolysis?
haemoglobinaemia
methaemalbuminaemia
haemoglobinuria
haemosiderinuria
what is haemoglobinaemia?
free Hb in the circulation
what is methaemalbuminaemia?
free haem joining with albumin in the blood
what colour is urine in haemoglobinuria?
pink
turns black when left to stand
name some possible causes of intravascular haemolysis
ABO incompatibility
G6PD deficiency
severe falciparum malaria
what tests should be done to confirm that a patient is in a haemolytic state?
FBC + blood film reticulocyte count serum unconjugated bilirubin serum haptoglobins urinary urobilinogen
what finding on blood film is suggestive of RBC membrane damage?
spherocytes
what finding on blood film is suggestive or RBC mechanical damage?
red cell fragments
what finding on blood film is suggestive of RBC oxidative damage?
heinz bodies
what does the direct coomb’s test do?
identifies antibodies bound to red cells
what are some possible causes of premature destruction of red cells?
autoimmune haemolysis
mechanical destruction
what is the “warm” autoantibody in autoimmune haemolysis?
IgG
name some causes of autoimmune haemolysis with IgG autoantibodies present
idiopathic
SLE
lymphoproliferative disorders
what is the “cold” autoantibody in autoimmune haemolysis?
IgM
name some causes of autoimmune haemolysis with IgM autoantibodies
idiopathic
infections
name some possible causes of mechanical red cell destruction
DICC HUS leaky heart avalves infections burns
what type of anaemia can be caused by a leaking heart valve?
microangiopathic haemolytic anaemia (MAHA)
what are some possible acquired causes of an abnormal RBC membrane?
liver disease
vit E deficiency
PNH
