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Molecular Basis Of Disease > Haemolytic Anaemia > Flashcards

Haemolytic Anaemia Flashcards

1
Q

What is haemolytic anaemia?

A

Anaemia due to shortened red blood cell survival

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2
Q

Describe the normal RBC lifecycle?

A

2x10^11 RBC/day in the bone marrow

RBC circulate for approx 120 days without nuclei or cytoplasmic organelles

Removal senescent RBC by reticular endothelial system of the liver and spleen

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3
Q

What is haemolysis?

A

Shortened red cell survival

Compensation by bone marrow to increase production

Increased young cells in circulation = resticulocytosis

RBC production unable to keep up with decreased RBC lifespan = decreased Hb

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4
Q

What are the clinical findings of haemolysis?

A
  • jaundice
  • pallor
  • fatigue
  • splenomegaly
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5
Q

What are chronic clinical findings of haemolysis?

A

Gallstones - pigment
Leg ulcers
Folate deficiency (increased use)

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6
Q

What would be observed in a peripheral blood film in haemolysis?

A

Nucleated red blood cells
Thrombocytosis
Neutrophillia with left shift
Polychromatophilia

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7
Q

What would the bone marrow findings look like in someone with haemolysis?

A

Erythronium hyperplasia of bone marrow
- normoblastic reactions
- reversal of M:E ration

Reticulocytosis
- mild (2-10%) or moderate (10-60%)

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8
Q

What would lab investigations for haemolysis show?

A

Increased uncojugated bilirubin

Increased LDH (lactate dehydrogenase)

Decreased serum haptoglobin protein that binds free Hb

Increased urobilinogen

Increased urinary hemosiderin

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9
Q

What are the 3 classifications of haemolytic anaemia?

A
  1. Inheritance
    - hereditary
    - acquired
  2. Site of RBC destruction
    - intravascular
    - extravascular
  3. Origin of RBC damage
    - intrinsic
    - extrinsic (infection)
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10
Q

What are the causes of intrinsic haemolytic anaemia?

A

Membrane defects

Enzyme defects
(G6PD, PK)

Haemoglobin defects

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11
Q

What are causes of extrinsic haemolytic anaemia?

A

Immune-mediated
- autoimmune (drug induced)
- alloimmune (haemolytic)

Drug and chemicals

Infections
- malaria

Hyperspenism

Red cell fragmentation
- mechanical trauma
- microangiopathic HA

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12
Q

Explain the normal process of RBC destruction

A

-RBC broken into globin, iron and protoporphyrin in macrophage
-Extravascular process
- porophyrin converted to bilirubin and transported to liver as uncojugated bilirubin
- liver produces biribulin glucuronides
-in the gut they get processed and re absorbed in the kidney

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13
Q

Explain the abnormal process of RBC destruction.

A
  • invascular process
  • RBC under lysis
  • haemoglobin remains in vasculature
  • haemoglobin converted to methaealbumin or is reabsorbed by the kidney
  • some haemoglobin found in urine (haemoglobinuria)
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14
Q

What membrane disorders can cause haemolytic anaemia?

A

Hereditary spherocytosis (defects in the verticals interactions)
-more common

Hereditary elliptocytosis (defects in the horizontal interactions)
- mutations in alpha and beta spectrum

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15
Q

What would be observed in a blood film for spherocytosis and elliptocytes?

A

Spherocytosis - sphere shape as unable to maintain the bioconcave shape. Cells become more susceptible to haemolysis.

Elliptocytes - tear drop cells, more like ovals.

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16
Q

What are the clinical features of hereditary spherocytosis?

A
  • asymptomatic to server haemolysis
  • neonatal jaundice
  • splenomegaly (removes damaged red blood cells so spleen becomes enlarged)
  • pigment gall stones (due to more bilirubin due to red blood cell degredation)
  • reduced EMA binding to band 3 (a test used to detect condition)
  • posative family history
  • negative direct antibody test
17
Q

How can defects in glucose 6 phosphate dehydrogenase cause oxidative haemolysis?

A

Oxidative stress occurs as no GSH (reduced glutathione) is made.
X LINKED - EFFECTS MALES MORE

Oxidation of Hb by oxidant radicals
- resulting in denatured Hb aggregates and forms Heinz bodies (bind to membrane)

Oxidised membrane proteins
- membrane proteins become phosphorylated
- reduced RBC deformability as they normally do to move through narrow blood vessels

Have protection against servere malaria

18
Q

What is the role of the HMP shunt in anaerobic respiration?

A
  • generates NADPH and reduced glutathione
  • reduced glutathione (GSH) protects the cell from the oxidative stress
  • REAUIRED GLUCOSE 6 PHOSPHATE DEHYDROGENASE
19
Q

What would be observed in a blood film for oxidative haemolysis?

A

Bite cells
Blister cells
ghost cells
Heinz bodies

20
Q

How does a pure age kinase deficiency cause haemolytic anaemia?

A

Autosomal recessive disorder

Low intracellular ATP concerntration
Less energy to maintain RBC shape and deformability
Less energy to regulate intracellular cation concentration via cation pumps (sodium and potassium pump)

Causes chronic non-spherocytic haemolytic anaemia

21
Q

What would be observed in a blood film of someone with private kinase deficiency?

A

Prickle cells

22
Q

What is thalassaemia?

A

A quantitative disorder

Caused by imbalance alpha and beta chain production
- Excess unpaired globin chains are unstable

Heterogeneous gp genetic disorders
And ineffective erythropoiesis (RBC production)

23
Q

What are the 4 types of thalassaemias?

A
  • hydrop foetalis
  • beta thalassaemia major
  • thalassaemia intermedia
  • thalassaemia minor
24
Q

What are the clinical features of BETA thalassaemia MAJOR?

A
  • servere anaemia
  • progressive hepatosplenomegaly
  • bone marrow expansion - facial bone abnormalities
  • mild jaundice
  • iron overload
  • intermittent infections, pallor
25
Q

What is jaundice?

A

When the skin or whiteness of your eyes turn yellow

26
Q

What is pallor?

A

Unhealthy pale appearance

27
Q

What would be observed in the peripheral blood of someone with beta thalassaemia major?

A

Microcytic hypochromic with decreased MCV (mean cell volume) , MCH (mean cell haemoglobin) , MCHC

Target cells, nucleated rbc, tear drop cells

Reticulocytes > 2%

28
Q

What is BETA thalassaemia trait MINOR?

A
  • Asymptomatic
  • often confused with Fe deficiency
  • alpha-thal trait often by exclusion
  • HbA2 increased in beta-thal trait
29
Q

What are the different types or severities of ALPHA Thalassaemia?

A

Hb Bart’s hydrops syndrome
- deletion of all 4 globin genes
- incompatable

HbH disease
- deletion of 3/4 globin genes
- common in SE Asia

That trait (minor)
- normal or mild HA
- MCV and MCH low

30
Q

What is thalassaemia intermedia?n

A

Disorder with clinical manifestation between major and minor

  • transfusion independent
  • diverse clinical phenotype
  • varying symptoms
  • bilirubin increased level
31
Q

What is sickle cell disease?

A

All diseases as a result of inherited HbS

HbS is caused by a single nucleotide substitution (point mutation)
Valine instead of glutamic acid
Insoluble Hb tetramer when deoxygenated (polymerisation)

  • HbSS is sicke cell anaemia (homozygous state)
  • HbSA is sickle cell trait (heterozygous)
  • HbS is beta thalassaemia
32
Q

What is haemoglobin sickling?

A

As the red blood cells travels around the blood there is exposer to oxygenated and deoxygenated states that lead to membrane distortion of red blood cells.

33
Q

What are the clinical features of sickle cell disease?

A

Painful crises

Aplastic crises

Infections due to hyposplenism

Acute sickling
- stroke
- chest syndrome
- splenic sequestration

Chronic sickling effects
- renal faliure
- avascular necrosis bone

34
Q

What are the laboratory features of sickle cell disease?

A

Anaemia

Reticulocytosis

Increased NRBC

Raised bilirubin

Low creatinine

35
Q

How can the diagnosis of sickle cell anaemia be confirmed in a lab?

A

Solubility test!

Expose blood to reducing agent
HbS precipitated
Positive in trait and disease

Molecular Basis Of Disease (32 decks)

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