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Kat's Pathology > Haemolytic Anaemias > Flashcards

Haemolytic Anaemias Flashcards

1
Q

What is the average lifespan of a red blood cell?

A

120 days.

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2
Q

What is the definition of haemolysis?

A

Defined as shortened red cell survival.

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3
Q

What are the two locations for haemolysis? (2)

A

Intravascular - within the circulation.

Extravascular - removal/destruction by the reticuloendothelial (RE) system.

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4
Q

How do people develop haemolytic disorders? (2)

A

Inherited or acquired.

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5
Q

What are some causes of extravascular haemolytic anaemia? (3)

A

Autoimmune.
Alloimmune.
Hereditary spherocytosis.

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6
Q

What are some intravascular causes of haemolytic anaemia? (7)

A 
Malaria. 
G6PD deficiency. 
Mismatched blood transfusions (ABO). 
Cold antibody haemolytic syndromes. 
Drugs 
Microangiopathic haemolytic anaemia. 
Paroxysmal nocturnal haemoglobinuria.
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7
Q

What are some types of microangiopathic haemolytic anaemia. (2)

A

Haemolytic uraemic syndrome.

Thrombotic thrombocytopenic purpura.

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8
Q

What parts of the RBC can be altered due to hereditary haemolytic anaemia? (3)

A

Membrane.
Red cell metabolism.
Haemoglobin.

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9
Q

How can the RBC membrane be affected in hereditary haemolytic anaemias? (2)

A

Cytoskeleton proteins.

Cation permeability.

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10
Q

How can haemoglobin be affected in hereditary haemolytic anaemia? (3)

A

Thalassaemia.
Sickle cell syndromes.
Unstable Hb variants.

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11
Q

What is important to ask in the history when considering blood disorders?

A

Family history.

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12
Q

What is the mode of inheritance of hereditary spherocytosis.

A

Autosomal dominant.

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13
Q

What are the consequences of haemolytic anaemias. 7)

A

Anaemia.
Erythroid hyperplasia with increased rate of red cell production and circulating reticulocytes.
Increased folate demand.
Susceptibility to effect of parvovirus B19 (virus has the ability to affect the developing erythroid blood cells in the bone marrow).
Propensity to gallstones (cholelithiasis)
Increased risk of iron overload.
Increased risk of osteoporosis.

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14
Q

What other hereditary disorder increases the risk of choleliathiasis in chronic haemolytic anaemia?

A

Gilbert’s syndrome.

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15
Q

What are the clinical features of chronic haemolytic anaemia? (5)

A 
Pallor. 
Jaundice. 
Splenomegaly. 
Pigmenturia. 
Family history.
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16
Q

What are the laboratory features of chronic haemolytic anaemia? (8)

A 
Anaemia. 
Increased reticulocytes. 
Polychromasia. 
Hyperbilirubinaemia. 
Increased LDH. 
Reduced/absent haptoglobins. 
Haemoglobinuria. 
Haemosiderinuria.
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17
Q

What are some proteins present in RBC membranes. (5)

A

GPC/D
RhAG
GPA
GPI

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18
Q

Name two disorders of red cell membrane present in haemolytic anaemias.

A

Hereditary spherocytosis.

Hereditary elliptocytosis.

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19
Q

What are the vertical interactions in hereditary spherocytosis. (4)

A

Band 3
Protein 4.2
Ankyrin
Beta-Spectrin

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20
Q

What are the horizontal interactions in hereditary elliptocytosis. (3)

A

Alpha-spectrin.
Beta-spectrin.
Protein 4.1

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21
Q

What is hereditary spherocytosis.

A

A genetic defect of red cell cytoskeleton.

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22
Q

What are the genetics of hereditary spherocytosis.

A

Family history in 75% (typically autosomal dominant)

25% are recessive or de novo mutations.

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23
Q

What is the osmotic fragility test and what condition is it used in?

A

In vitro red cells show increased sensitivity to lysis in hypotonic saline (osmotic fragility test)

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24
Q

What tests are used in hereditary spherocytosis (2)

A

Osmotic fragility test.

Eosin-5-Maleimide dye.

25
Q

What occurs in hereditary spherocytopsis with eosin-5-maleimide dye?

A

Reduced binding.

26
Q

What do RBC films look like in hereditary spherocytosis?

A

Red cells lose central pallor (round red cells).

27
Q

What do RBC films look like in hereditary eliptocytosis.

A

Elliptical red blood cells - central pallor remains.

28
Q

What do RBC films look like in hereditary pyropoikilocytosis.

A

Oddly shaped RBCs, with irregular cell membranes.

29
Q

What is Glucose-6-Phosphate Dehydrogenase deficiency?

A

Lack of G6PD enzyme, which catalyses the first step in pentose phosphate (hexose monophosphate) pathway - generates NADPH required to maintain intracellular glutathione (GSH)

30
Q

What is the mode of inheritance of G6PD deficiency?

A

X-linked.

31
Q

Approximately how many people are affected by G6PD deficiency.

A

400 million worldwide.

32
Q

Where is G6PD deficiency particularly prevalent?

A

In areas of malarial endemicity - it has a protective effect.

33
Q

What are the clinical effects of G6PD deficiency? (3)

A

Neonatal jaundice.
Acute haemolysis (triggered by oxidants/infection - steady state is asymptomatic)
Chronic haemolytic anaemia is rare.

34
Q

What can be used to stain Heinz bodies inside RBCs?

A

Methylviolet.

35
Q

What can provoke haemolysis in G6PD deficiency? (5)

A 
Anti-malarials (primaquine). 
Antibiotics (sulphonamides, ciprofloxacin, nitrofurantoin) 
Other drugs (dapsone, vitamin K). 
Fave beans. 
Mothballs.
36
Q

What are some key metabolic pathways in RBCs which can lead to haemolysis if they are defective? (6)

A

Embden-meyerhof - ATP, NADH.
Hezone monophosphate shunt (pentose phosphate) - NADPH.
Rapoport-Luebering shuttle - 2,3-DPG.
Nucleotide metabolism.
Glutathione biosynthesis.
Cytochrome b5 reductase - methomoglobin reduction.

37
Q

What is the most common deficiency in pyruvate kinase deficiency?

A

Glycolytic pathway defect.

38
Q

What type of nucleotides are toxic to RBCs?

A

Pyrimidine.

39
Q

What do RBCs look like in pyrimidine 5’-nucleotidase deficiency?

A

Basophilic stipling in the RBCs.

40
Q

What conditions are associated with basophilic stipling in RBCs? (2)

A

Pyrimidine 5’-nucoetidase deficiency.

Lead poisoning.

41
Q

What are distinctive features of haemolytic disorders (4)

A

Age of onset - neonatal or early infancy tends to be more likely to be an inherited disorder.
Pattern of haemolysis - episode or chronic (episodic characterises a G6PD deficiency).
Mode of inheritance.
Other somatic defects (some of the glycolytic disorders are associated with musculoskeletal disease).

42
Q

What are the first line investigations in a patient presenting with unexplained haemolysis (8)

A 
Direct antiglobulin test. 
Urinary haemosiderin/haemoglobin. 
Osmotic fragility. 
G6PD and pyruvate kinase activity. 
Haemoglobin separaton A anf F%. 
Heinz body stain. 
Ham's test/flow cytometry of GPU-linked proteins. 
Thick and thin blood films.
43
Q

What does a direct antiglobulin test look for?

A

Presence of immunoglobulins on RBCs.

Excludes autoimmune haemolysis.

44
Q

What does urinary haemosiderin/haemoglobin detect?

A

Intravascular haemolysis.

45
Q

What does an osmotic fragility test detect?

A

Hereditary spherocytosis (defects in cell membranes)

46
Q

What does haemoglobin separation A and F% detect?

A

Haemoglobin disorders.

47
Q

What does a Heinz body stain detect?

A

Evidence of haemolytic haemolysis.

48
Q

What does a ham’s test detect?

A

Looks at the sensitivity of RBCs to lysis.

49
Q

What does a thick and thin blood film detect?

A

Malaria.

50
Q

What are the principles of management of haemolytic anaemia? (7)

A

Folic acid supplementation.
Avoidance of precipitating factors.
Red cell transfusion/exchange.
Immunisation against blood borne viruses.
Monitor for chronic complications.
Cholecystectomy for symptomatic gallstones.
Splenectomy if indicated.

51
Q

What conditions are indications for a splenectomy in haemolytic anaemias. (5)

A

OK deficiency and some other enzymopathies.
Hereditary spherocytosis.
Severe elliptocytosis/pyropoikilocytosis.
Thalassaemia syndromes.
Immune haemolytic anaemia.

52
Q

What are the risks with splenectomy in haemolytic anaemias

A

Risk of overwhelming sepsis.

53
Q

What is the most common cause of sepsis in a patient who has undergone a splenectomy.

A

Capsulated bacteria (e.g. pneumococcus)

54
Q

What is the best way to prevent sepsis in a patient who has undergone a splenectomy. (2)

A

Penicillin prophylaxis and immunisation.

55
Q

What is the criteria for a splenectomy in haemolytic anaemia? (5)

A 
Transfusion dependence. 
growth delay. 
Physical limitation haemoglobin <8g/dL
Hypersplenism 
Age (not <3 years, but before 10 years to maximise prepubertal growth)
56
Q

What is electrospray ionisation-mass spectrometry? (3)

A

Separates molecules on the basis of their molecular mass – resolves differences in protein structure.

57
Q

What are the benefits of electrospray ionisation-mass spectroscopy? (2)

A

Fast.

Low-cost.

58
Q

What is electrospray ionisation - mass spectroscopy useful for analysing RBCs?

A

Red cells are ideal analyte - single protein at high concentraitons.

Kat's Pathology (105 decks)

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