Haemolysis and Haemolytic Anaemia Flashcards
What is haemolysis?
the premature breakdown of red blood cells
What is a RBC’s normal lifespan?
about 120 days
Where can haemolysis occur?
intravascular - in the circulation
extravascular - in the reticuloendothelial system
What is the reticuloendothelial cell system?
macrophages of liver, spleen and bone marrow
What may you find on examination with haemolysis?
jaundice
hepatosplenomegaly
What are the consequences of haemolysis?
excess red blood cell breakdown products
erythroid hyperplasia
How would you know if there was increased red cell destruction?
anaemia (normal or increased MCV)
increased bilirubin (unconjugated, from haem breakdown)
increased serum lactic dehydrogenase (released from RBC)
increased urinary urobilinogen
How would you know if there was increased RBC production?
increased reticulocytes
Features of extravascular haemolysis?
spleno+/-hepatomegaly
4 features of intravascular haemolysis?
methaemalbuminaemia
haemoglobinuria (red brown urine)
decreased plasma haptoglobin
haemosiderinuria
What is methaemalbuminaemia?
some free Hb is broken down in the circulation to produce haem and globin - haem combines with albumin
What is Coombs/antiglobulin test?
determines if its an immune cause of haemolysis
What does a positive Coombs result indicate?
an immune cause of haemolysis
What are the immune mediated acquired causes of haemolytic anaemia?
drug induced
autoimmune haemolytic anaemia
isoimmune - acute transfusion reaction, haemolytic disease of the newborn
What are the non immune mediated acquired causes of haemolytic anaemia?
direct coombs test negative autoimmune haemolytic anaemia
infection
microangiopathic haemolytic anaemia
What is autoimmune haemolytic anaemia?
extravascular haemolysis and spherocytosis
mediated by autoantibodies
How is autoimmune haemolytic anaemia classified?
according to optimum binding temp to RBCs
warm and cold
Describe warm autoimmune haemolytic anaemia.
IgG mediated
body temp
treatment: steroids, immunosuppression +/- splenectomy
Describe cold autoimmune haemolytic anaemia
IgM mediated
chronic anaemia made worse by cold
treatment: keep warm
What infection can cause acquired haemolytic anaemia?
malaria
What are causes of autoimmune haemolytic anaemia?
idiopathic
secondary: CLL, lymphoma, drugs, infection, AI conditions e.g. SLE
What are the hereditary causes of haemolysis?
enzyme defects e,g, glucose-6-phosphate dehydrogenase deficiency, pyruvate kinase deficiency
membrane defects e.g. hereditary spherocytosis
haemoglobinopathy e.g. sickle cell disease, thalassaemia
What happens in spherocytosis?
less flexible red blood cells
trapped in spleen
extravascular haemolysis
What happens in extravascular haemolysis?
hyperplasia at site of destruction
release of protoporphyrin –> unconjugated jaundice
normal blood products in excess
What happens in intravascular haemolysis?
RBC destroyed in circulation and spill contents
abnormal blood products in excess
