Haemolysis Flashcards
what is hameolysis?
premature red cell destruction
what are the features of red blood cells that make them more susceptible to damage?
Biconcave shape
Limited metabolic reserve (no mitochondria)
Can’t generate new proteins once in the circulation (no nucleus)
haemolysis can be…
compensated or decompensated
what is compensated haemolysis?
Increased red cell destruction compensated by increased red cell production
= Hb Maintained
what is decompensated haemolysis?
decompensated haemolysis
o Increased rate of red cell destruction exceeding bone marrow capacity for red cell production = Hb Falls
what are the consequences of haemolysis?
o Erythroid hyperplasia (increased bone marrow red cell production)
o Excess red cell breakdown products eg bilirubin
what is the bone marrow response to haemolysis?
- Reticulocytotic
2. Erythroid hyperplasia
how does reticulocytosis appear on blood film?
- Non nucleated
* polychromsia (ribosomal RNA)
what are the different classifications of haemolysis?
Extravascular Intravascular Premature destruction Abnormal cell membrane Abnormal Red Cell Metabolism Abnormal Haemoglobin
where does extravascular haemolysis occur?
reticuloendothelial system (liver and spleen)
what are the causes of extravascular haemolysis?
majority of causes of haemolysis?
what are the blood products in extravascular haemolysis?
normal products in excess
which forms of bilirubin are found in extravascular haemolysis?
- Unconjugated bilrubinaemia
* Urobilinogenuria
where does intravascular haemolysis occur?
within the circulation
what are the blood products in intravascular haemolysis?
abnormal
what are the causes of intravascular haemolysis?
ABO incompatible blood transfusion
G6PD deficiency
Severe falciparum malaria (Blackwater Fever)
PNH,PCH
the blood products in intravascular haemolysis are found as?
- Haemoglobinaemia (free Hb in circulation)
- Methaemalbuminaemia
- Haemoglobinuria:
- Haemosiderinuria
premature destruction of normal red cells is an
acquired process
premature destruction of red cells can be either:
immune or mechanical
what are the two types of immune premature destruction of normal red cells?
Autoimmune and
Alloimmune Haemolysis
what are the causes of warm autoimmune haemolysis?
o Idiopathic (commonest) o Autoimmune disorders (SLE) o Lymphoproliferative disorders (CLL) o Drugs (penicillins, etc) o Infections
what are the causes of cold autoimmune haemolysis?
o Idiopathic
o Infections (EBV, mycoplasma)
o Lymphoproliferative disorders
what are the causes of immune response alloimmune haemolysis?
Haemolytic transfusion reaction
Immediate (IgM) predominantly intravascular
Delayed (IgG) predominantly extravascular
what are the causes of passive transfer of antibody in alloimmune haemolysis?
Haemolytic disease of the newborn - Rh D, ABO incompatibility, Others eg anti-Kell
what are the mechanical causes of Premature destruction of normal red cells?
Disseminated intravascular coagulation
Hemolytic uremic syndrome (eg E. coli O157)
TTP
Leaking heart valve (microangiopathic hemolytic anaemia)
Infections e.g. Malaria
Burns
what are the acquired causes of haemolysis caused by abnormal cell membranes?
Liver Disease (Zieve’s Syndrome) Vitamin E deficiency Paroxysmal Nocturnal Haemoglobinuria
what are the congenital causes of haemolysis caused by abnormal cell membranes?
- Reduced membrane deformability
- Increased transit time through spleen
- Oxidant environment in spleen causes extravascular red cell destruction
- Hereditary Spherocytosis
what are the congenital causes of abnormal red cell metabolism leading to haemolysis?
- Reduced membrane deformability
- Increased transit time through spleen
- Oxidant environment in spleen causes extravascular red cell destruction
- Hereditary Spherocytosis
what condition causes abnormal haemoglobin that can lead to haemolsyis?
Sickle Cell Disease
what type of anaemia is haemolytic anaemia?
normocytic or macrocytic
how can haemolytic anaemia be diagnosed?
- Confirm Haemolytic State
2. Identify Cause
how is the haemolytic state confirmed in haemolytic anaemia?
- FBC (+ Blood Film)
- Reticulocyte Count
- Serum unconjugated bilirubin
- Serum haptoglobins
- Urinary urobilinogen
how is the cause of haemolytic anaemia identified?
- History and examination : Genetic/Acquired
- Blood Film
- Specialist investigations (Direct Coombs’ test and others)
what are the features on blood film looked at in haemolytic anaemia?
o Membrane damage (spherocytes)
o Mechanical damage (red cell fragments)
o Oxidative damage (Heinz bodies)
o Others e.g.. HbS (sickle cells)
