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Week 3 - haematology > Haemolytic anaemia > Flashcards

Haemolytic anaemia Flashcards

1
Q

What is the definition of haemolytic anaemia?

A
  • Anaemia related to reduced red blood cell lifespan

* No blood loss and no haematinic deficiency (folate/B12/iron)

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2
Q

Describe the haematology if red cell lifespan is 20-100 days

A

Compensated haemolytic state
•Hb normal
•Reticulocytes increased
•(unconjugated) bilirubin increased

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3
Q

Describe the haematology if red cell lifespan is less than 20 days

A 
Haemolytic anaemia 
•Hb decreased
•Reticulocytes increased
•Bilirubin incereased
•Splenomegaly (often palpable)
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4
Q

Why may someone in a chronic haemolytic state have gall stones?

A

Due to the increased bilirubin, causing pigment gall stones

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5
Q

What is hyposplenic state?

A

Rises from encapsulated organism pneumococcus, meningococcus, haemophilus

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6
Q

What broad categories that cause the congenital haemolytic anaemias?

A
  • Abnormalities of the RBC membrane
  • Abnormalities of the RBC enzymes
  • Haemoglobinopathies
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7
Q

Hereditary spherocytosis

A
  • Congenital haemolytic anaemia due to abnormalities of the red blood cell membrane
  • Autosomal dominant
  • RBCs spherocytic and polychromatic
  • Jaundice
  • Splenomegaly
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8
Q

Explain pyruvate kinase deficiency anaemia

A
  • required for the conversion of ADP to ATP so ATP becomes depleted and red cells haemolyse
  • results in chronic extravascular haemolytic anaemia
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9
Q

Explain glucose 6 phosphate dehydrogenase deficiency

A
  • required for turning NADP to NADPH
  • acute episodic intravascular haemolysis (but for most of the time normal) from oxidative stress
  • X linked recessive
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10
Q

In a glucose 6 phosphate dehydrogenase deficiency, what can cause episodes of acute haemolysis?

A 
Oxidative stress:
•Favism 
•Drugs 
- antimalarials
- sulphonamides 
- others
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11
Q

What are the types of acquired haemolytic anaemias?

A
  1. Autoimmune: warm type or cold type
  2. Isoimmune e.g. haemolytic disease of newborn
  3. Non immune e.g. fragmentation haemolysis
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12
Q

Explain when intravascular haemolysis may take place

A
  • when there has been mechanical trauma to the red cell e.g. defective mechanical heart valves
  • Following ABO incompatible blood transfusion resulting in the production of anti-A and/or anti-B IgM antibodies
  • Malaria
  • Cold IgM autoantibodies
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13
Q

What are the causes of cold autoimmune haemolytic anaemia?

A 
•Primary: idiopathic
•secondary; 
- infection-mycoplasma pneumoniae 
- infectious mononucleosis 
- lymphoproliferative disorders
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14
Q

What are the main laboratory findings in intravascular haemolysis?

A
  • anaemia, reticulocytosis and raised unconjugated bilirubin
  • haemoglobinaemia and haemoglobinuria
  • haemosiderinuria
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15
Q

Explain why haemosiderin may appear in the urine due to intravascular haemolysis

A
  • there is an increased amount of haemoglobin
  • haemoglobin saturates the binding protein in the plasma, haptoglobin
  • Excess haemoglobin is filtered at the glomerulus resulting in haemoglobinuria
  • The renal tubules reabsorb some haemoglobin from the urine which is broken down to form haemosiderin which can then also appear in the urine
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16
Q

Explain what happens in extravascular haemolysis

A
  • It occurs in the reticuloendothelial system, particularly in the spleen
  • It is often related to the production of warm IgG autoantibodies
17
Q

Describe what happens in extravascular haemolysis caused by the production of warm antibodies

A
  • IgG attaches to the red cell antigen and damages the membrane
  • The RBCs become spherocytic and are phagocytosed by the RES, particularly the spleen
  • As a result the spleen becomes enlarged
18
Q

What are the causes of warm type autoimmune haemolytic anaemia?

A 
•primary: idiopathic - 55-60%
• secondary:
- lymphoproliferative disorders e.g. chronic lymphocytic leukaemia 
- neoplasms
- SLE
- connective tissue disorders 
- drugs
19
Q

State the different autoimmune haemolytic anaemias

A
  • Drug induced - the drug acts as a hapten
  • immune complex
  • autoimmune
20
Q

Explain the direct Coombs test

A
  • Add anti human immunoglobulin

* If there are antibodies (with or without complement) the red cells will agglutinate

21
Q

Explain the indirect Coombs test

A
  • Used to detect antibodies floating freely in the blood to check prior to transfusion
  • Plasma from the patient is mixed with a sample of blood
  • Anti-human immunoglobulin is added, if agglutination occurs it is positive
22
Q

What is the treatment of cold autoimmune haemolytic anaemia?

A
  • If due to a mycoplasma infection it is self limiting

* if idiopathic keep the patient warm (IgM antibodies won’t fix to the red blood cells)

23
Q

How do you treat warm autoimmune haemolytic anaemia?

A
  • Stop any drugs
  • Use steroids if idiopathic
  • Immunosuppression
  • Splenectomy
24
Q

Describe haemolytic disease of the newborn

A
  • Rhesus negative mother with a rhesus positive baby
  • some red cells from the baby leak into the mothers circulation
  • RhD+ cells raised IgG antibodies which can cross the placenta, attacking the baby’s red cells and cause haemolytic anaemia

Week 3 - haematology (17 decks)

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