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Haematology > Haemolytic Anaemias > Flashcards

Haemolytic Anaemias Flashcards

1
Q

What is a haemolytic anaemia?

A

An anaemia caused by a reduced lifespan of red blood cells

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2
Q

What is the normal life span of red blood cells?

A

120 days

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3
Q

How can haemolytic anaemias be divided?

A
  • Intravascular vs Extravascular

- Inherited vs Acquired

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4
Q

Name causes of intravascular haemolytic anaemia

A
  • Malaria
  • G6PD deficiency
  • Blood transfusion mismatch
  • Drugs
  • MAHAs (HUS, TTP, paroxysmal nocturnal haemoglobinuria)
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5
Q

How can inherited causes of haemolytic anaemias be divided?

A
  • Membrane defects
  • Enzyme defects
  • Haemoglobinopathies
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6
Q

Name examples of membrane defect haemolytic anaemias

A
  • Hereditary spherocytosis

- Hereditary elliptocytosis

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7
Q

Name examples of enzyme defect haemolytic anaemias

A
  • G6PD deficiency
  • Pyruvate kinase deficiency
  • Pyramidine nucleotidase deficiency
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8
Q

What are the consequences to haemolysis?

A
  • Anaemia
  • Erythroid hyperplasia
  • Increased folate demand
  • Susceptibility to parvovirus B19
  • Cholelithiasis
  • Iron overload
  • Osteoporosis
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9
Q

What are the clinical features of haemolytic anaemias?

A
  • Pallor
  • Jaundice
  • Splenomegaly
  • Pigmenturia
  • Family History
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10
Q

What laboratory results may be found in a patient with haemolytic anaemia?

A
  • Anaemia
  • Increased reticulocytes
  • Polychromatasia
  • Increased bilirubin (unconjugated)
  • Increased LDH
  • Haemoglobinuria
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11
Q

How can you divide causes of acquired haemolytic anaemias?

A
  • Immune modulated

- Non-immune modulated

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12
Q

Name immune modulated causes of acquired haemolytic anaemia

A
  • Autoimmune (warm or cold)

- Alloimmune (haemolytic transfusion reactions)

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13
Q

Name non-immune modulated cauases of acquired haemolytic anaemia

A
  • Mechanical causes (valve, trauma)
  • MAHAs (HUS, TTP, PNH)
  • Infections and drugs
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14
Q

What is hereditary spherocytosis? What causes it? How do you diagnose it? What is the treatment?

A

An autosomal dominant condition where red blood cells are spherical in shape.

It is caused by errors in vertical communication between the cytoskeleton and the membrane, caused by deficiencies in spectrin (or ankyrin).

It is diagnosed by blood film and the osmostic fragility test.

It is treated with folic acid supplements, and possible splenectomy.

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15
Q

What is hereditary elliptocytosis?

A

This is usually a benign condition, caused by mutations in spectrin. Can be asymptomatic or fatal.

If homozygous, the phenotype is described as hereditary pyropoikilocytosis, which is a very bad form of haemolytic anaemia.

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16
Q

What are the first line investigations in a suspected case of haemolytic anaemia?

A
  • Direct antiglobulin test (autoimmune anaemia)
  • Osmotic fragility (hereditary spherocytosis)
  • G6PD +/- PK activity
  • Heinz bodies (oxidative haemolysis)
  • Thick and Thin blood film (malaria)
17
Q

What is G6PD?

A

Glucose - 6 - phosphate dehydrogenase. It is an enzyme that produces NADPH which facilitates glutathione production. Its deficiency is of the most common inherited haemolytic anaemias in the world.

18
Q

Describe G6PD deficiency, its epidemiology, its clinical features, its diagnoses and its treatment.

A

It is an enzyme deficiency which is usually asymptomatic until triggered by a stressor.

It is most common in Asian Mediterranean and middle eastern communities. It is the most common hereditary haemolytic anaemia, and the most common cause of kernicterus in neonatal jaundice.

It appears as a rapidly appearing anaemia and jaundice, episodically. During an attack, the blood film may show bite cells, and Heinz bodies. It is usually precipitated by stress, drugs (primaquine, aspirin, sulfonamides) or broad bean ingestion.

It is diagnosed with an enzyme assay, 2-3 months after the last attack.

It is treated conservatively, avoiding the triggers involved. Genetic screening is offered, and transfusion is done only in severe cases.

19
Q

What is pyruvate kinase? Describe its deficiency.

A

It is an enzyme involved in the glycolytic pathway; its deficiency causes severe neonatal jaundice, splenomegaly and haemolytic anaemia. Most will not require treatment, but those who do may have a transfusion or splenectomy.

20
Q

How does one manage a case of haemolytic anaemia?

A
  • Folate supplementation
  • Avoiding factors (G6PD deficiency)
  • RBC transfusion (severe cases)
  • Immunisation (Hepatitis A and B)
  • Monitoring
  • Splenectomy (in certain indications)
21
Q

What are the indications for splenectomy? What must one be aware of?

A
  • Reduced growth
  • Aged between 3 and 10
  • Very low haemoglobin (<80g/l)
  • PK deficiency, hereditary spherocytosis, thalassaemia, Gilbert’s

Those with a splenectomy are at increased risk of bacterial sepsis, particularly capsulated bacteria (pneumococcus, meningococcus)

22
Q

What is sickle cell disease?

A

This is an umbrella term to describe states associated with the sickling of RBCs.

23
Q

What is the aetiology of sickle cell disease?

A

There is a single base mutation, changing GAG to GTG, causing the formation of HbS instead of HbA.

24
Q

What are the different phenotypes of sickle cell disease?

A

HbSS: severe sickle cell disease
HbSA: sickle cell carrier, asymptomatic unless stressor

25
Q

What are the clinical features of sickle cell disease?

A

It will often present at the ages of 3-6 months, which coincides with the decreasing levels of HbF.

Features:

  • Anaemia
  • Splenomegaly
  • Folate deficiency
  • Gallstones
  • Aplastic crises with parvovirus B19

Features of vaso-occlusion and infarction: SICKLED MP

  • Stroke
  • Infection
  • Crises
  • Kidney disease (papillary necrosis)
  • Liver (gallstones)
  • Eyes (retinopathy)
  • Dactilitis
  • Mesenteric ischaemia
  • Priapism
26
Q

How can the clinical features of sickle cell disease differ depending on onset?

A

Children:

  • Strokes
  • Splenomegaly
  • Splenic crises

Teenagers:

  • Failure to grow
  • Gallstones

Adults:

  • Splenomegaly
  • Hyposplenism
  • CKD
27
Q

How do you diagnose sickle cell disease?

A
  • Blood film: sickle cells and target cells
  • Sickle solubility test
  • Hb electrophoresis
  • Guthrie test (at birth)
28
Q

How is sickle cell anaemia treated?

A

Painful crises: treat with analgaesia

  • Folic acid
  • Penicillin V
  • Pneumovax (and other immunisations)
  • Hydroxycarbamide
29
Q

What is thalassaemia?

A

This is a disease that involves unbalanced Hb synthesis, with an excess of either alpha or beta chains.

30
Q

What is beta thalassaemia?

A

An excess of alpha chains, due to a reduced production of beta chains.

31
Q

What are the clinical features of beta thalassaemia?

A

Skull bossing, hairs on end on skull x-ray

32
Q

What are the different phenotypes of beta thalassaemia?

A

Minor: asymptomatic carrier
Intermedia: moderate anaemia
Major: 3-6 months severe anaemia, all major features of beta thalassaemia (bossing, bone deformities)

33
Q

How do you diagnose beta thalassaemia?

A

Hb electrophoresis

34
Q

How is beta thalassaemia treated?

A
  • Blood transfusions
  • Desferrioxamine
  • Stem cell transplant is curative
35
Q

What is alpha thalassaemia?

A

An excess of beta chains due to a deletion in the alpha chain synthesis (up to 4 of the chains deleted)

36
Q

What are the different types of alpha thalassaemia?

A 
Trait (1/2 chains deleted): asymptomatic, mild anaemia
Disease (3 deleted): moderate anaemia, splenomegaly
Hydrops foetalis (4 deleted): incompatible with life
37
Q

What is Hydrops Foetalis?

A

This is an alpha thalassaemia where all four alpha chains are deleted, which is incompatible with life.

Haematology (13 decks)

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