Haemolysis Flashcards
What is haemolysis?
premature red cell destruction
Why are RBCs susceptible to damage?
biconcave shape to transmit through circulation
limited metabolic reserve and rely on glucose metabolism for energy
they cannot generate new protiens once in circulation
What is compensated haemolysis?
increased red cell destruction that is compensated by increased red cell production
What is decompensated haemolysis?
increased red cell destruction exceeds bone marrow capacity for RBC production
What’re the consequences of haemolysis?
erythroid hyperplasia - increased bone marrow red cell production
excess red blood cell breakdown products eg bilirubin
What’re the signs of haemolysis?
reticulocytosis - have RNA so stain darker
erythroid hyperplasia
What two ways can haemolysis be classed?
extravascular
intravascular
What is extravascular haemolysis?
RBCs are taken up by the reticuloendothelial system - spleen and liver - and are destroyed - causes splenomegaly
causes the release of protoporphyrin = normal breakdown products in excess -> jaundice and gallstones
What is intravascular haemolysis?
RBCs are destroyed in the circulation, spilling their contents
this causes abnormal products - life threatening
What abnormal products are produced in intravascular haemolysis?
haemoglobinaemia - free Hb in circulation
methaemalbuminaemia
haemoglobinuria - pink urine that turns black on staining
haemosiderinuria
What causes intravascular haemolysis?
G6PD deficiency
ABO incompatibility
severe falciparum malaria
What are causes of premature haemolysis of normal RBCs?
autoimmune haemolysis
alloimmune haemolysis
What are the two types of autoimmune haemolysis?
Warm IgG
Cold IgG
What are causes of Warm IgG autoimmune haemolysis?
idiopathic autoimmune disorders - SLE lymphoproliferative disorders - CLL drugs - penicillin infections
What causes Cold IgG autoimmune haemolysis?
idiopathic
infections - EBV, mycoplasma
Lymphoproliferative disorders
What identifies autoimmune haemolysis?
Direct Coombs test - tests for antibodies already attached to RBCs
What is alloimmune haemolysis?
antibodies develop to forgein red cells
What are the two types of alloimmune haemolysis?
immune response
passive transfer of antibody
What is immune response alloimmune haemolysis?
haemolytic transfusion reaction - can be delayed (IgG - extravascular) or acute (IgM - intravascular)
What is passive transfer of antibody alloimmune haemolysis?
haemolytic disease of the newborn - ABO, RhD incompatibility
mechanical destruction - HUS, TTP, leaking heart valve (microangiopathic haemolytic anaemia), severe burns, malaria
What aquired abnormal cell membrane defects lead to haemolysis?
liver disease -> cirrhosis -> zieves syndrome (alcoholics, polycromatic macrocytes, irregularly contracted cells)
vitamin E deficiency
paroxysmal nocturnal haemoglobinuria
What congenital abnormal cell membrane defects lead to haemolysis?
Hereditary Spherocytosis
What is hereditary spherocytosis?
autosomal dominant
reduced membrane deformability causing increased transit time through the spleen which means the oxidatiev environment in the spleen causes extravascular red cell destruction
How does hereditary spherocytosis present?
gallstones
jaundice
splenomegaly
How is hereditary spherocytosis treated?
splenectomy
What congenital abnormalities to red cell metabolism can lead to haemolysis?
G6DP deficiency
What congenital abnormalities to haemoglobin can lead to haemolysis?
sickle cell disease
