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IMED2002 > Haemolytic Anaemia > Flashcards

Haemolytic Anaemia Flashcards

1
Q

What is haemolytic anaemia?

A

It is anemia due to shortened RBC lifespan

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2
Q

What is the lifespan of cells which are haemolytic?

A

Less than 120 days (less than 15 days survival)

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3
Q

What does the bone marrow usually do in response to haemolytic anaemia? What is the stimulus for this?

A

It increases erythropoiesis, driven by EPO stimulus

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4
Q

In haemolysis red cells are destroyed by…

A

Macrophages

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5
Q

Globin chains are degraded to which of the following?

(a) carbohydrates
(b) bilirubin
(c) haptoglobin
(d) amino acids
(e) folate

A

(d) amino acids

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6
Q

Outline what happens to haem when it is degraded during haemolytic anaemia

A

Haem binds to haptoglobin, then is degraded to protoporphyrin and then is metabolised to bilirubin which is excreted through faeces or urine.

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7
Q

Outline what happens to iron when degraded by haemolytic anaemia

A

Iron binds to transferrin and then is stored as ferritin in macrophages. Hence, it is released and recycled.

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8
Q

Red cell destruction is extravascular when it is in…

A

Macrophages

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9
Q

Red cell destruction is intravascular when it is within…

A

Blood vessels

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10
Q

Outline the markers for haemolytic anaemia:

A

1) Increased bilirubin due to extravascular haem breakdown
2) Increased LDH
3) Reduced haptoglobins due to Hb-haptoglobin complexes
4) Spherocytes
5) Fragmented red cells (schistocytes)
6) Polychromasia

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11
Q

Which of the following would count as good evidence that the patient has haemolytic anaemia:

(a) elliptocytes
(b) plasma cells in the blood
(c) macrocytes
(d) nucleated blood cells in blood
(e) microcytes

A

Nucleated blood cells in the blood - which should be in the bone marrow. Increased RBC production and compensation by the bone marrow leads to some early progenitor cells like reticulocytes and nucleated red blood cells in the blood. They come out before they are ready, and polychromasia is another evidence for increased RBC production.

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12
Q

The plasma has a red tinge due to the destruction of the RBCs. True or False:

A

True

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13
Q

Is Lactose Dehydrogenase a good marker for hemolysis?

A

Yes, because it is present in the RBCs and is released into the plasma due to haemolysis

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14
Q

Distinguish between the laboratory features of extravascular and intravascular haemolytic anaemia:

A

Extravascular:
Polychromasia and altered RBC shape
LDH elevated
Bilirubin elevated

Intravascular:
Fragmented red cells
Low haptoglobin 
Hb in plasma
Haemosiderin in urine
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15
Q

Explain the key clinical features of haemolytic anaemia?

A

Jaundice (due to bilirubin in the plasma)
Gallstones (due to excess bilirubin)
Splenomegaly
Expanded bone marrow (chronic erythroid hyperplasia)
Megaloblastic anaemia (due to folate deficiency as the folate stores run out when there is an increased drive to make new cells)

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16
Q

What causes haemolytic anaemia?

A

Hereditary causes like:
Membrane defect: hereditary spherocytosis
Enzyme defect: G6PD and PK deficiency
Globin chain defect: haemoglobinopathies

There are also acquired causes

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17
Q

Explain why RBC membranes must be deformable?

A

RBC membranes must be deformable and stable. It is the abnormal RBC membrane deformability, which leads to a reduced RBC lifespan, and hereditary disorders.

Phospholipid & membrane proteins determine this disorder. Mutations in the genes of membrane skeletal proteins,.

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18
Q

Hereditary spherocytosis is the least common inherited haemolytic anaemia. True or False?

A

False, it is the most common

19
Q

How is hereditary spherocytosis inherited? Which protein is mutated?

A

Autosomal dominant
Defect in any/all structural RBC membrane proteins
(Spectrin, ankyrin, band 3)

20
Q

Explain Hereditary Spherocytosis:

A

RBC is less deformable, and it loses the membrane when passing through the spleen microcirculation
RBCs become spherical, rigid, and then are destroyed, with no central palor
(think sphere = membrane shape)

21
Q

What is the result of DAT (direct antibody test) / Direct Coombs test in hereditary spherocytosis?

(a) positive because antibodies are not coating the RBC
(b) negative because antibodies are coating the RBC
(c) negative because antibodies are not coating the RBC
(d) positive because antibodies are coating the RBC

A

C - negative because antibodies are most likely not attached to your RBCs

22
Q

Outline treatment options for hereditary spherocytosis

A

Splenectomy

Folic acid

23
Q

How is herditary elliptocytosis inherited?

(a) Autosomal dominant
(b) Autosomal recessive
(c) X-linked recessive
(d) X-linked dominant

A

a - autosomal dominant

24
Q

Is hereditary elliptocytosis milder than hereditary spherocytosis?

A

Yes, milder than HS as only 10% have haemolysis

25
Q

Hereditary elliptocytosis is characterised by which mutation and what cells are characteristic of this disorder?

A

Mutations in spectrin

Elliptical shaped red cells

26
Q

What is the most common inherited genetic defect in RBC enzymes?

A

Glucose-6-phosphate dehydrogenase

27
Q

How is G6PD deficiency inherited?

A

X-chromosome (males affected)

28
Q

What characterises G6PD deficiency? Triggers, and what happens in G6PD deficiency

A

RBCs become susceptible to oxidant stress
Triggers of oxidant haemolysis are drugs, fava beans, infection, hypoxia
As a result the oxidised Hb is removed

29
Q

How does G6PD deficiency look like on the blood film?

A

It looks like the RBCs have been “bitten”
Hb becomes oxidized as the reducing power of NADPH no longer functions
The Hb precipitates and then when the RBC passes through the spleen, the Hb is removed/pitted out from the spleen

29
Q

How does G6PD deficiency look like on the blood film?

A

It looks like the RBCs have been “bitten”
Hb becomes oxidized as the reducing power of NADPH no longer functions
The Hb precipitates and then when the RBC passes through the spleen, the Hb is removed/pitted out from the spleen

30
Q

What is the result of insufficient pyruvate kinase?

A

Insufficient ATP made, as pyruvate kinase is a key enzyme in metabolising glucose in the RBCs by anaerobic glycolysis through the Embden-Meyerhof pathway
PK catalyses the final step of glycolysis and is required to make ATP
The RBC membranes get rigid and results in cell death (haemolytic anaemia)

31
Q

How can you partly improve PK - related haemolytic anaemia?

A

through splenectomy

32
Q

Inheritance of Pyruvate Kinase is:

(a) Autosomal dominant
(b) Autosomal recessive
(c) X-linked dominant
(d) X-linked recessive

A

b - autosomal recessive

33
Q

What is the clinical presentation of PK deficiency?

A

Occasionally this haemolysis is compensated (mild)
In severe cases, it can present in the neonatal period and then the child doesn’t survive
Splenomegaly in the child

34
Q

How does PK deficiency look like on the blood film?

A

Prickle shaped RBCs
Spicules come off the RBC
Acanthocyte

35
Q

Explain auto-immune haemolytic anaemia:

1) what is it
2) causes
3) blood film
4) DAT result
5) treatment

A

Auto-immune haemolytic anaemia

What is it:
Auto-antibodies are directed against own RBCs (self = auto)

Causes are:
Idiopathic, leukaemia, auto-immune syndromes

Blood film:
Spherocytes (no central pallor due to loss of membrane), small and dark Hb
Polychromasia due to increased reticulocytes
Nucleated red cells as a result of BM response to anaemia
Underlying disease can also be seen eg. leukaemia

DAT result:
Positive direct antiglobulin test (DAT) result as antibodies are coating the RBCs

Bone marrow response: 
Erythroid hyperplasia (compensatory, to make new RBCs)

Treatment:
Suppress the immune system with corticosteroids
Treat the cause (eg. leukaemia)
Remove the spleen which is the site of cell destruction

36
Q

Explain allo-immune haemolytic anaemia, and haemolytic disease of the newborn

A

Allo-immune haemolytic anaemia:

Is when antibody made by one individual reacts against the RBCs of another individual
Like in transfusions or newborns

In newborns the transplacental passage of maternal RBC antibodies bind to fetal RBCs and the maternal antibodies destroy the fetal RBC

Usually seen in a Rh(D) negative mother, and a Rh(D) positive fetus
When the anti-Rh(D) antibodies are made by the mother in the 1st pregnancy when exposed to the D antigen
Then the subsequent pregnancy is affected when the maternal anti-D crosses the placenta and binds to, and destroys the fetal Rh(D) positive RBCs

37
Q

Explain fragmentation haemolysis (what it is, what it leads to, blood film)

A

Mechanical damage to RBCs, when RBCs are exposed to an abnormal surface
MAHA (microangiopathic haemolytic anaemia that results from physical damage to the red cells following the occlusion of arterioles and capillaries as a result of fibrin deposition or platelet aggregation
Damaged small blood vessels can also cause fragmentation haemolysis
this leads to anaemia and schistocytes (fragments) on the blood film
Intravascular haemolysis (in the BV)

38
Q

List and describe other causes of haemolytic anaemia:

A

1) Liver disease
2) Renal failure

both alter the RBC membrane and then the cells can’t get through the spleen

3) Infections

Severe bacterial sepsis and disseminated intravascular coagulation can lead to fragmented red cells, fragmented haemolytic anemia (MAHA)

Malaria, infection with plasmodium
Parasitic infection inside the RBCs, leading to RBC burst which releases Hb
Can detect Hb in urine (dark urine)

Clostridium infection
Microspherocytes

4) Severe burns

leading to small, contracted red blood cells (as the RBCs are dehydrated & very small)

39
Q

A patient is looking yellow, they have dark urine and low Hb levels. You suspect them to have haemolytic anaemia, describe the initial laboratory tests you will prescribe. What do you expect to see and explain your reasoning behind:

A

1) Haptoglobin levels
Expect to see it decreased as it binds free Hb

2) LDH
Expect to see it elevated as it is released from RBCs when the lyse

3) Reticulocyte count
Expect to see it elevated as the bone marrow response to anemia

4) Bilirubin
Expect to see it elevated, as it is increased when Hb breaks down

40
Q

What is MAHA (microangiopathic haemolytic anaemia)?

A

Microangiopathic haemolytic anaemia is a term that is used to describe the anaemia that results from physical damage to the red cells following the occlusion of arterioles and capillaries as a result of fibrin deposition or platelet aggregation.
RBCs can be fragmented, can expect to see schistocytes in the peripheral blood smear.

41
Q

Pyruvate kinase deficiency and liver disease both result in which type of cell on the blood film?

A

Acanthocytes

42
Q

Severe renal dysfunction can lead to which cell type on the blood film?

A

Burr cells (echinocytes)

IMED2002 (12 decks)

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