Haemolysis Flashcards
What is the definition if haemolysis?
Pemature red cell destruction
i.e. shortened red cell survival
What 3 reasons mean red cells are susceptible to damage?
- They need biconcave shape
- Limited metabolic reserve (no mitochondria)
- Can’t generate new proteins once in circulation (no nucleus)
What is compensated haemolysis?
Increased red cell destruction compensated by increased red cell production
What is haemolytic anaemia (decompensated haemolysis)?
Increased rate of red cell destruction exceeding bone marrow capacity for red cell production
What are consequences of haemolysis?
Erythroid hyperplasia
Excess red cell breakdown products e.g. biliruben
What is Erythroid hyperplasia?
Increased bone marrow red cell production
What is the bone marrow response to haemolysis?
Reticulocytosis
Erythroid hyperplasia
Are reticulocytes nucleated ells?
No
What is ribosomal RNA labelled with to count flourescent cells?
Flourochrome
What is extravascular haemolysis?
Red cells taken up by reticuloendothelial system (liver and spleen mainly)
What is intravascular haemolysis?
Red cells destroyed within circulation
Describe extravascular red cell destrucion?
Commoner
Hyperplasia at site of destruction
Release of protoporphyrin
Which is more likely to be life threatening, intra or extra vascular haemolysis?
Intra
Why is intravascular so bad?
Red cells spill their contents into circulation
What are the 4 potential problems that can arise from intravascular haemolysis?
- Haemoglobinaemia (free Hb in circulation)
- Methaemalbuminaemia
- Haemoglobinuria (pink urine, turns black on standing)
- Haemosiderinuria
What are causes of intravascular haemolysis?
ABO incompatible blood transfusion
G6PD deficiency
Severe falciparum malaria (blackwater fever)
PNH,PCH (rare)
What are causes of extravascular haemolysis?
Pretty much all other causes of haemolysis
What are investigations for haemolysis?
Confirm haemolytic state. FBC (+blood film) Reticulocyte count Serum unconjugated biliruben Serum haptoglobins Urinary urobilinogen
Name 4 things that should be looked for on blood film?
Red cell fragments
Spherocytes
Heinz bodies
Sickle cells
Name 1 specialist test for haemolysis?
Direct Coombs’ test
What are 4 classifications based on site of red cell defect?
- Premature destruction of normal red cells (immune or mechanical)
- Abnormal cell membrane
- Abnormal red cell metabolism
- Abnormal haemoglobin
What are two types of autoimmune haemolysis?
Warm (IgG)
Cold (IgM)
What are types of warm (IgG)?
Idiopathic Autoimmune (SLE) Lymphoprolifrative disorders (CLL) Drugs (penicillin) Infections
What are types of cold (IgM)?
Idiopathic
Infections (EBV, Mycoplasma)
Lymphoproliferative disorders
What does a Coomb’s test do?
Identifies antibody (and complement) bound to own red cells
What are two types of Alloimmune haemolysis?
Immune response (antibody produced) Passive transfer of antibody
What is Immune response alloimmune haemolysis?
Haemolytic tranfusion reaction
Immeadiate, (IgM) predominantly intravascular
Delayed (IgG) predominantly extravascular
What is passive transfer to antibody alloimmune haemolysis?
Haemolytic disease of the newborn
RhD
ABO incompatibility
Others e.g. anti-Kell
What are causes of acquired haemolysis?
Disseminated intravascular coagulation Haemolytic uraemic syndrome (e.g. E.coli 0157) TTP leaking heart valve Infectious e.g. malaria
What is MAHA?
Mechanical valve related Microangiopathic haemolytic anaemia - red cell fragmentation as a result of mechanical (extrinsic damage)
When are microspherocytes seen?
In burns related haemolysis
What are membrane defect causes of haemolysis?
Liver disease (Zieve's syndrome) Vitamin E deficiency paroxysmal Nocturnal haemoglobinuria
What is seen in Zieve’s syndrome?
Anameia
polychromatic macrocytes
Irregular contracted cells
What are genetic causes of haemolysis?
Reduced membrane deformability
Increased transit time through spleen
Oxidant environment in spleen causes extravascular red cell destruction
Hereditary spherocytosis
