Haemolysis Flashcards
what is haemolysis?
red cell destruction
two types of haemolysis
- compensated
2. decompensated (haemolytic anaemia)
consequences of haemolysis
bone marrow= erythroid hyperplasia and reticulocytosis
excess breakdown products e.g. bilirubin
what does reticulocytosis look like on blood film?
polychromasia
reticulocytes stain blue due to the presence of RNA
haemolysis classification based on site
- extravascular
2. intravascular
what does extravascular haemolysis cause?
hyperplasia at site of destruction (hepatosplenomegaly)
release of protoporphyrin
normal products in excess
what does protoporphyrin cause?
unconjugated bilirubin- jaundice + gall stones
urobilinogenuria
what is intravascular haemolysis?
red cells are destroyed within the circulation spilling their contents
what do products of intravascular haemolysis cause?
haemoglobinaemia (free Hb)
methaemalbuminaemia
haemoglobinuria (pink urine that turns black on standing)
haemosiderinuria
what is pink urine that turns black on standing seen in?
intravascular haemolysis due to haemoglobinuria
what is the consequence of intravascular haemolysis?
abnormal products can be life-threatening
causes of intravascular haemolysis
ABO incompatible blood transfusion
G6PD deficiency
severe falciparum malaria
diagnosis of hereditary spherocytosis
positive Schumm’s test
schistocytes
blood film of G6PD deficiency
bite cells
blister cells
Heinz bodies
immune causes of premature red cell destruction
autoimmune haemolysis (warm IgG versus cold IgM) alloimmune haemolysis
mechanical causes of premature destruction of red cells
DIC HUS (E. coli 0157) TTP leaking heart valve/ MAHA malaria burns
what are microspherocytes?
red cells sheared when pass through capillaries damaged by burns
diagnosis of warm IgG and cold IgM AI haemolysis
DAT
what is alloimmune haemolysis
immune response to Ab produced (transfusion reaction) or passive transfer of antibody (HDFN)
acquired causes of abnormal cell membrane in RBC
- Zieve’s syndrome
- vitamin E deficiency
- paroxysmal nocturnal haemoglobinuria
triad in Zieve’s syndrome
haemolysis
alcoholic liver disease
hyperlipidaemia
genetic causes of abnormal RBC membrane
hereditary spherocytosis
what is hereditary spherocytosis?
defect in RBC membrane proteins causing reduced deformability, increased transit time in spleen and the oxidant environment causes extravascular destruction
diagnosis of hereditary spherocytosis
polychromasia
red cells have lost central pallor
cause of abnormal red cell metabolism
GP6D deficiency
diagnosis of haemolysis
FBC, reticulocyte count, serum unconjugated bilirubin, serum haptoglobins
urinary urobilinogen
blood film
DAT
what is haptoglobins?
protein produced by the liver that attaches to free Hb in blood
what do spherocytes on blood film indicate?
membrane damage
what do red cell fragments on blood film indicate?
mechanical damage
what do Heinz bodies on blood film indicate?
oxidative damage
what is DAT?
Direct Coomb’s test (looks at antigens on red cell surface)
