Haemolytic Anaemia Flashcards
What is haemolytic anaemia?
Anaemia related to reduced RBC lifespan. There is no blood loss or haematinic deficiency
What are the haematological results of a compensated haemolytic anaemia?
- Normal Hb
- Raised reticulocytes,
- Raised unconjugated bilirubin.
What are the haematological results of an (uncompensated) haemolytic anaemia?
- Low Hb,
- Raised reticulocytes,
- Raised bilirubin,
- Palpable spleen.
Name and describe an example of a congenital haemolytic anaemia
Hereditary spherocytosis.
It is an autosomal dominant disease where the RBCs are spherocytic and polychromatic. It presents with jaundice and splenomegaly
What is the possible treatment for hereditary spherocytosis?
Splenectomy and hyposplenic prophylaxis. Patients who are hyposplenic present with Howell Jolly bodies.
What is hypospenic state?
Occurs due to splenectomy and resultant encapsulated organisms infections such as pneumococcus, meningococcus and haemophilus. Treated with immunisations and long term penicillin V
Name inherited haemolytic anaemias
- Hereditary spherocytosis,
- Haemoglobinopathies (sickle cell and thalassaemia
- Abnormalities of RBC enzymes (G6PD deficiency, Pyruvate kinase def anaemia)
What are the different defective enzymes pathways that result in anaemias
- Pyruvate kinase deficiency anaemia. Glycolysis pathway - Pyruvate kinase deficiency results in ATP depletion causing RBCs to haemolyse. Autosomal recessive.
2, Pentose phosphate pathways. X-linked recessive. Where a deficiency in glucose 6 phosphate dehydrogenase results in depleted levels of NADPH (normal function is to protect against oxidative stress)
What are the clinical features of enzyme deficiencies causing haemolytic anaemia
- Pyruvate kinase def anaemia - Chronic, extravascular haemolytic anaemia. because RBCs haemolyse as they are depleted of ATP.
- Glucose 6 phosphate dehydrogenase def anaemia - acute episodic intravascular haemolysis. Normally asymptomatic but get episodes of acute haemolysis when exposured to oxidative stress (eg, consumption of favamines, or certain drugs like antimalarials or sulphonamides)
What are the different types of acquired haemolytic anaemias?
Autoimmune - Warm types (IgG) and cold type (IgM)
Isoimmune - haemolytic disease of the newborn.
Non immune - fragmentation haemolysis
What are some causes of fragmentation haemolysis?
- Involved mechanical breakdown of cells. Examples include:
- Malfunctioning mechanical heart valve,
- Haemolytic uraemic syndrome,
- Disseminated intravascular dissemination
What is cold autoimmune haemolytic anaemia?
IgM autoantibodies and complement targeted against RBCs
- Can be caused by mycoplasma infections, idiopathic or associated with lymphoproliferative disorders.
- Blood film shows agglutination
Describe features of warm autoimmune haemolytic anaemia
IgG autoantibodies with/without complement attack against on RBC.
- Can be idiopathic, caused by other autoimmune disease, lymphoproliferative disorders or drug induced.
- Blood film will show polychromatic spherocytes
Describe drug induced autoimmune haemolytic anaemia
Drug acts as hapten (molecule that illicit an immune response) which usually causes mild haemolysis. If the drug and antibody form an immune complex then it causes severe haemolysis
Describe a direct coombs test?
Anti-human immunoglobulin is used to react with antibodies on the red blood cell surface. If positive then it indicates AIHA and HDN.
Describe an indirect coombs test
Patients plasma is mixed with donor blood. Antihuman immunoglobulin is then added to detect the presence of RBC antibodies
Whats the treatment for autoimmune haemolytic anaemia?
Cold (IgM) - Self-limiting mycoplasma infection and keep patient warm.
Warm (IgG) - Stop any drugs then give steroids, immunosuppression and splenectomy
Describe haemolytic disease of the new born
This occurs when a Rhesus negative mother has a Rhesus positive baby. Some of the foetal RBCs enter the maternal circulation, stimulating an immune response. The resulting IgG antibodies passes through the placenta and attacks the baby.
Describe features of hereditary spherocytosis
- Autosomal dominant condition, common in northern europeans where there is reduced RBC survival as they are destroyed by the spleen
