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IMED2002 UWA > Haemolytic anaemia and Haemoglobinopathies > Flashcards

Haemolytic anaemia and Haemoglobinopathies Flashcards

1
Q

What is haemolytic anaemia?

A

Anaemia due to shortened RBC lifespan.

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2
Q

How does the bone marrow respond to drop in RBC lifespan?

A

Usually bone marrow responds and increases erythropoiesis

Red cell production can increase 6 - 8 times

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3
Q

At what RBC lifespan does anaemia occur?

A

<15 days

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4
Q

What causes haemolytic anaemia?

A

RBC survival <15 days

Haematinic deficiency (esp. folate)

Bone marrow disease

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5
Q

What happens if haemolysis occurs in the blood vessels?

A

Hemoglobinemia

Methemalbuminemia

hemosiderinuna

Haemoglobinuria (It mixes with plasma and then gets excreted in urine)

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6
Q

What are signs of RBC destruction?

A

Increased bilirubin (haem breakdown)

Increased LDH (lactate dehydrogenase)

Reduced haptoglobins (Hb-haptoglobin complex)

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7
Q

What blood film evidence indicates red blood cell damage in haemolytic anaemia?

A

Spherocytes (no area of central pallor)

Fragmented red blood cells (schistocytes)

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8
Q

What blood film evidence indicates increased RBC production increase in haemolytic anaemia?

A

Increased reticulocyte production (polychromasia) [not ready yet]

Nucleated RBCs (they should be in bone marrow but are released early)

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9
Q

What are the clinical features of haemolytic anaemia?

A

Anaemia

Jaundice: bilirubin in plasma

Pigment gallstones may occur

Splenomegaly

Ankle ulcers: sickle cell anaemia

Expanded bone marrow

Aplastic crises: parvovirus

Megaloblastic anaemia

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10
Q

What are pigment gallstones caused by?

A

bilirubin is concentrated causing gallstones

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11
Q

What are ankle ulcers caused by?

A

Sickle cell anaemia

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12
Q

What is expanded bone marrow?

A

Erythroid hyperactivity causes increases in BM size (especially in young people)

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13
Q

What is aplastic crises? What is it caused by?

A

Caused by switching off of erythroid activity in the bone marrow. Can be caused by parvovirus infection

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14
Q

Why does haemolytic anaemia show up as megaloblastic anaemia as well?

A

It causes overactivity of folate use and that results in folate deficiency

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15
Q

What causes hereditary haemolytic anaemia?

A

Membrane defect: hereditary spherocytosis

Enzyme defect: G6PD (Glucose 6 phosphate dehydrogenase) deficiency

Globin chain defect: haemoglobiniopathies

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16
Q

What causes acquired haemolytic anaemia?

A

Immune haemolytic anaemia (most common acquired haemolytic anaemia)

Fragmentation haemolysis

Oxidative haemolysis

Liver disease

Infections, renal disease, other

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17
Q

Which membrane proteins are defected in hereditary spherocytosis?

A

Spectrin (peripheral protein)

Ankyrin

Band 3 (integral protein)

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18
Q

How is hereditary spherocytosis inherited?

A

Autosomal dominant

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19
Q

What is the most commonly inherited anaemia?

A

hereditary spherocytosis

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20
Q

Where are RBCs removed in hereditery spherocytosis?

A

In the spleen the RBCs lose their membrane and so red blood cells become spherical and then are destroyed

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21
Q

How does hereditary spherocytosis present in patients?

A

Fluctuating anaemia and jaundice

Sphenomegaly and gall stones

Lab tests show:

Spherocytes on blood film

Polychromasia

Negative DAT

Positive EMA (band-3) [Eosin 5 Maleimide which is a die that binds to band 3]

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22
Q

How is hereditary spherocytosis treated?

A

Splenectomy (spleen is the site of haemolysis)

Folic acid (to avoid folate deficiency)

cholecystectomy

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23
Q

What is a problem with splenectomy that should be considered?

A

People are more prone to bacterial infection when spleen is removed

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24
Q

What is hereditary elliptocytosis?

A

Autosomal dominant condition caused by mutations in spectrin.

It is asymptomatic in most people but 10% have haemolysis

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25
Q

What is G6PD deficiency?

A

Glucose 6 Phosphate Dehydrogenase deficiency

The most common red cell enzyme disorder worldwide (>200 million people affected)

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26
Q

What does G6PD do?

A

Enzyme in the hexose monophosphate shunt which generates reducing power as NADPH

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27
Q

What causes G6PD deficiency?

A

Mutation in gene on X-chromosome.making it more common in males than females

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28
Q

Does Australia have high G6PD deficiency?

A

No, But it must be known because it does exist in some people and people that migrate to australia

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29
Q

What is the problem with G6PD?

A

RBC susceptible to oxidant stress.

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30
Q

What triggers haemolysis in G6PD?

A

Oxidative stress caused by eating raw beans as well as infection, hypoxia, and drugs

31
Q

What kind of red cells form on the blood film?

A

“Bite” or blister cells

32
Q

What happens after oxidative stress is triggered?

A

Intravascular haemolysis and oxidised Hb is removed

33
Q

How is G6PD deficiency treated?

A

Remove / stop / treat offending agent

Treat infection

Transfuse blood if necessary

34
Q

What happens between crises caused by oxidative stress in G6PD deficiency?

A

RBC count returns to normal

35
Q

What does pyruvate kinase do?

A

It is the enzyme that catalyses the last step of glycolysis and is required to make ATP

36
Q

What results if pyruvate kinase is deficient?

A

Insufficient ATP leads to cell death resulting in haemolytic anaemia

37
Q

How is pyruvate kinase deficiency inherited?

A

Autosomal recessive inheritance

38
Q

How does pyruvate kinase present itself clinically?

A

Mild: occasional compensated haemolysis

Severe: can present in neonatal period with failure to thrive and splenomegaly

39
Q

What do RBCs look like in pyruvate kinase deficiency?

A

Prickle-shaped RBCs

40
Q

How is pyruvate kinase deficiency diagnosed?

A

Pyruvate kinase assay

41
Q

What causes immune haemolytic anaemia?

A

It is idiopathic in most cases and in some cases it is caused by cancer cells (if leukemia/lymphoma is treated we can bring haemolysis under control)

42
Q

Where does haemolysis take place in immune haemolytic anaemia?

A

In the spleen

43
Q

What is allo-immune haemolytic anaemia?

A

Newborn blood damaged by antibodies to Rh in mother.

44
Q

How can drugs cause immune haemolytic anaemia?

A

Antibody can form against a RBC-drug complex

Antibiotics

45
Q

How can immune haemolytic anaemia be tested for?

A

Using a direct antiglobulin test:

Blood sample of someone with immune haemolytic anaemia containing antibodies attached to RBCs is put in a test tube.

Coomb’s reagent is then added to the mixture and agglutination gives a positive test result

46
Q

What does autoimmune haemolytic anaemia look like on blood film?

A

Spherocytes are produced (this condition’s blood film is identical to spherocytosis)

Polychromasia with increased reticulocytes

Nucleated RBCs

Underlying disease (eg. leukemia)

47
Q

What is fragmentation haemolysis?

A

A micro-angiopathic haemolytic anaemia where RBCs are damaged structurally

48
Q

What causes fragmentation anaemia?

A

Heart valve pinhole lesion

Fibrin strands in vasculature (can be secondary damage)

Damaged blood vessels

Physically damaged RBCs due to mechanical movements of the body.

Red cell fragmentation

49
Q

What kind of haemolysis does fragmentation haemolysis cause?

A

Intravascular haemolysis

50
Q

What does fragmentation haemolysis look like on blood film?

A

Schistocytes

51
Q

What does severe liver disease and renal dysfunction result in?

A

intravascular haemolysis

52
Q

What cells are seen on blood film of severe liver disease?

A

Acanthocytes

53
Q

What cells are seen on blood film of people with severe renal dysfunction?

A

Burr cells (echinocytes) [think of echidna]

54
Q

What are echinocytes?

A

Echinocyte (from the Greek word echinos, meaning ‘hedgehog’ or ‘sea urchin’), in human biology and medicine, refers to a form of red blood cell that has an abnormal cell membrane characterized by many small, evenly spaced thorny projections. A more common term for these cells is burr cells.

55
Q

What types of infections lead to severe haemolysis?

A

Severe bacterial sepsis

Malaria

Clostridium welchii: cause microspherocytes in PB film

56
Q

What other conditions can severe bacterial sepsis cause?

A

Causes DIC and fragmented red cells

57
Q

What species of plasmodium can cause anaemia?

A

P. vivax, falciparum, ovale, malariae

Trophozoites; schizonts; gametocytes

58
Q

What does Clostridium welchii related anaemia look like on blood film?

A

Microspherocytes in PB film

59
Q

Where are alpha and beta globin chains located in genome?

A

2 alpha genes on chromosome 16

2 beta genes on chromosome 11

60
Q

What else does chromosome 11 contain around the beta globin chain?

A

The delta and gamma genes

61
Q

What are the most common causes of monogenic diseases in the world?

A

Haemoglobinopathaties

62
Q

What is thalassaemia caused by?

A

Deficient synthesis of globin chains

63
Q

What are the classifications of thalassemia?

A

Trait: Carriers

Intermedia: shows up at times of stress

Major: symptomatic all the time

64
Q

What is beta thalassemia caused by?

A

reduced beta chain production due to mutations in beta globin gene.

65
Q

What happens when gene for beta thalassemia is homozygous?

A

When homozygous the condition is present at 3 - 6 months and causes severe anaemia due to loss of fetal gamma chain on which it was dependent.

66
Q

What happens when gene for beta thalassemia is heterozygous?

A

Asymptomatic

67
Q

Why does thalassemia cause swelling of the spleen and liver?

A

Because they are overworked trying to remove faults RBCs

68
Q

How are beta thalassemia patients treated?

A

These people are transfusion dependent.for entire life (3 - 4 bags of packed blood cells a month) but transfusion brings in too much iron so iron is removed by iron chelators.

69
Q

What do the faces of people with thalassemia major look like?

A

Hair standing on end and cheek bones are prominent

70
Q

How many genes control alpha thalasemia?

A

4 alpha globin chains

71
Q

How many alpha globin genes are missed in thalassemia minor?

A

1 or 2

72
Q

How many alpha globin genes are missed in haemoglobin H disease?

A

3

73
Q

How many alpha globin genes are missed in Hb barts hydrops fetalis?

A

4

74
Q

What causes sickle cell anaemia?

A

A mutation encoding haemoglobin beta forming crystal and HbSS. Sickle shaped red cells can occlude blood vessels

IMED2002 UWA (29 decks)

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