Haemolytic Anaemia Flashcards
What is Haemolytic Anaemia?
- Premature destruction of RBCs before their normal lifespan of 120 days
- Symptoms begin to appear when the bone marrow does not compensate sufficiently to the Haemolysis
How do you categorise Haemolytic Anaemia?
- Inherited or Acquired
=> Acquired Haemolytic Anaemia can also be categorised as:
- Immune
- Non-immune
=> Can also be categorised as intravascular (within circulation) or extravascular (spleen or liver)
What are the causes of Inherited Haemolytic Anaemia?
=> Related to problems with RBCs
Membrane disorder => Hereditary Spherocytosis
Metabolism => G6PD deficiency
Haemoglobinopathies => Sickle cell, thallassaemia
What are the causes of Acquired Haemolytic Anaemia?
=> Immune related
- Autoimmune (warm AIHA or cold AIHA)
- Alloimmune (eg. transfusion reactions)
=> Non-immune related:
- Paroxsymal Nocturnal Haemoglobinuria
- Microangiopathic Haemolysis
- Valve Haemolysis
- Infection
- Drugs
=> Different types of Microangiopathic Haemolysis:
- Thrombotic Thrombocytopenic Purpura
- Disseminated Intravascular Coagulation
- Haemolytic Uraemic Syndrome
- This type of haemolytic anaemia is characterised by schistocytes on blood film
What are the findings in suspected Haemolytic Anaemia?
=> Intravascular Haemolytic Anaemia:
- High unconjugated bilirubin
- High LDH (enzyme found in RBCs - lactate dehydrogenase)
- High Reticulocytes
- Low Haptoglobin
- Haemoglobinuria
- Haemoglobinaemia
- Hemosiderinuria
-> Extravascular Haemolytic Anaemia:
- High unconjugated bilirubin
- High LDH
- High Reticulocytes
- Normal Haptoglobin levels
- No Haemoglobinuria
- No Haemogloinaemia
- No Hemosiderinuria
What are the investigations in suspected Haemolytic Anaemia?
=> Direct Coombs Test
- Blood sample from patient with immune mediated haemolytic anaemia is taken
- Coombs reagent is added
- Positive test result - RBCs agglutinate
=> Indirect Coombs Test
- Used as pre natal testing and before blood transfusion
=> Coombs test is only positive for AIHI
=> Blood film
- Spherocytes seen in AIHI and Hereditary Spherocytosis
What is haptoglobin?
- Molecule that binds to free floating haemoglobin
What is Warm Autoimmune Haemolytic Anaemia?
- Form of extravascular haemolytic anaemia
- IgG antibodies bind to surface of RBCs when there is an increase in temperature
- Promote phagocytosis out of circulation
- Part of red cell membrane is lost in process
=> Causes:
- Neoplasm
- Drugs (Methyldopa)
- Autoimmune conditions
Form of extravascular Haemolysis
What is Cold Autoimmune haemolytic Anaemia?
- IgM mediated
- Associated with Acrocyanosis and Raynauds
- Often triggered by mycoplasma pneumoniae
=> Causes:
- Neoplasm
- Infection
=> Form of intravascular haemolysis
What are the clinical features of Haemolytic Anaemia?
- Jaundice
- Hepatosplenomegaly
- Gallstones
- Leg ulcers
What is the management of warm AIHA?
- Steroids
- Blood as needed
- Rituximab
What is the management of cold AIHA?
- Keep warm
- Blood warmers
- Occasional chemo if caused by lymphoproliferative disease
What is Thrombotic Thrombocytopoenic Purpura?
- Pro-thrombotic state where the sheer force on RBCs destroys them
What is the management of Thrombotic Thrombocytopoenic Purpura?
- Blood transfusion but not plasma
- High dose steroids
- Blood
- Folic acid
- Aspirin and prophylactic LMWH when platelets recover
How to determine whether haemolytic anaemia is intravascular or extravascular?
=> Extravascular Haemolysis:
- Splenic hypertrophy
- Splenomegaly
=> Intravascular Haemolysis:
- Increased free plasma haemoglobin
- Methaemalbuminaemia
- Decreased plasma haptoglobin
- Red brown urine due to high unconjugated bilirubin
- Haemosederinuria
What is Hereditary Spherocytosis?
- Autoimmune dominant condition
- Normal biconcave shape of RBCs is lost and replaced by a sphere shaped red blood cell (spherocytes)
What is the clinical presentation of Hereditary Spherocytosis?
- Failure to thrive
- Jaundice
- Gallstones
- Splenomegaly
- Aplastic crisis in cases of parvovirus infection
What is the main investigation in suspected Hereditary Spherocytosis?
EMA binding
Spherocytosis not diagnostic as they are seen in Warm Haemolytic Anaemia too
What is the management of Hereditary Spherocytosis?
=> Acute haemolytic crisis:
- Transfusion if necessary
- Supportive
=> Long term:
- Folate
- Splenectomy
What is G6PD deficiency?
- X linked recessive condition
- The deficiency in the enzyme means the RBCs undergo haemolysis due to oxidative stress
What are the clinical features of G6PD deficiency?
- Neonatal jaundice
- Intravascular haemolysis
- Gallstones
- Splenomegaly
- Heinz body’s on blood film (also seen in alpha thallasaemia so not diagnostic)
- Bite cells on blood film
What is the main investigation in suspected G6PD deficiency?
G6PD enzyme assay
What drugs cause haemolysis in patients with G6PD deficiency?
- Anti malarials
- Ciprofloxacin
- Sulph group drugs
