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HAEMATOLOGY > Haemolysis > Flashcards

Haemolysis Flashcards

1
Q

What is haemolysis?

A

Premature red cell destruction

i.e. shortened red cell survival

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2
Q

Why are red cells susceptible to damage?

A
  • biconcave shape
  • limited metabolic reserve (no mitochondria)
  • Can’t generate new proteins as no nucleus
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3
Q

What is meant by a compensated haemolysis?

A
  • Increased red cell destruction compensated by increased red cell production
    => Hb Maintained
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4
Q

When do patients with haemolysis become anaemic?

A

Rate of red cell destruction > red cell production

=> Hb Falls

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5
Q

What are the main consequences of haemolysis?

A

Erythroid hyperplasia (+reticulocytosis)

Excess red cell breakdown products eg billirubin

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6
Q

How does reticulocytosis appear on a blood film?

A

polychromasia

- different coloured cell due to RNA in reticulocytes picking up purple pigment

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7
Q

What is the difference between intravascular and extravascular haemolysis?

A

Extravascular
- Taken up by reticuloendothelial system (spleen and liver)

Intravascular
- destroyed within the circulation

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8
Q

WHich of extra/intravascular haemolysis is more common?

A

Extravascular

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9
Q

WHat does extravascular haemolysis cause?

A
  • Hyperplasia at destruction site (hepato/splenomegaly)
  • Release of protoporphyrin
  • Unconjugated bilrubinaemia
    => Jaundice/ Gall stones /Urobilinogenuria

Normal products, just in excess

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10
Q

What does intravascular haemolysis cause?

A
  • destroyed in the circulation
    => Haemoglobinaemia (free Hb in circulation)
    => Methaemalbuminaemia
    => Haemoglobinuria: pink urine, black on standing
    => Haemosiderinuria

These are Abnormal products

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11
Q

What are the rare cases that intravascular haemolysis does occur?

A
  • ABO incompatible blood transfusion
  • G6PD deficiency
  • Paroxysmal Noctural Haemoglobinuria (PNH)
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12
Q

How would you investigate a patient with suspected haemolysis?

A 
FBC (+ BLOOD FILM)
Reticulocyte count
Serum unconjugated bilirubin
Serum haptoglobins
Urinary urobilinogen
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13
Q

HOw can investigations help us narrow down the cause of haemolysis?

A

Hx - give indication of Genetics/FHx

Blood Film: Membrane damage (spherocytes)
Mechanical damage - valve replacement
=> (red cell fragments)
Oxidative damage (Heinz bodies)
Others e.g.. HbS (sickle cells)

Specialist investigations (Direct Coombs’ test)

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14
Q

What causes of haemolysis are acquired?

A
  1. Premature destruction
    - Immune - auto/alloimmune, to own Ab or ones pt has been exposed to previously
    - Mechanical - metal heart valve
  2. Abnormal cell membrane
    - Liver disease (Zieve’s)
    - Vit E deficiency
    - PNH
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15
Q

What causes of haemolysis are congenital?

A
  1. Abnormal red cell metabolism
    - e.g. G6PD deficiency
  2. Abnormal haemoglobin
    e. g. sickle cell anaemia
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16
Q

What can cause autoimmune haemolysis?

A

Warm Ab (IgG)

  • Idiopathic (commonest)
  • Autoimmune disorders (SLE)
  • Lymphoproliferative disorders
  • Drugs (penicillins)
  • Infections

Cold (IgM)

  • Idiopathic
  • Infections
  • Lymphoproliferative disorders
17
Q

WHat are the potential causes of Alloimmune haemolysis?

A

Transfusion reaction
Immediate (IgM) - intravascular
Delayed (IgG) - extravascular

Passive transfer

  • Haemolytic disease of the newborn
  • Rh D
18
Q

What else can cause mechanical RBC destruction?

A

Disseminated intravascular coagulation (DIC)
Haemolytic uraemic syndrome (eg E. coli O157)
Infections e.g. Malaria

19
Q

What physical signs can become apparent in Beta Thalassemia Major?

A

Bony deformities due to erythroid hyperplasia
e.g. frontal bossing of skull

  • marrow cavity expansion
20
Q

How would Beta Thalassemia appear on a blood film?

A
  • hypo/micro targets
  • nucleated rbc’s
  • pappenheimer bodies
21
Q

A 22 year old female presents with Splenomegaly and Intermittent mild jaundice. She is also troubled by recurrent Gallstones. Her Father had splenectomy in young adulthood for gallstones.

What hereditary disorder could cause this clinical picture, and how is it inherited?

A

Hereditary Spherocytosis

  • chronic extravascular haemolysis
  • Dominant inheritance

HAEMATOLOGY (24 decks)

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