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3MB Haematology > Haemolysis > Flashcards

Haemolysis Flashcards

1
Q

Define haemolysis

A

Premature red cell destruction
i.e. shortened red cell survival

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2
Q

Why are red cells susceptible to damage?

A

They need to have a biconcave shape to transit the circulation successfully

They have limited metabolic reserve and rely exclusively on glucose metabolism for
energy (no mitochondria)

Can’t generate new proteins once in the circulation (no nucleus)

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3
Q

Define compensated haemolysis

A

Increased red cell destruction compensated by increased red cell production i.e Hb maintained

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4
Q

What is haemolytic anaemia?

A

Destruction of red blood cells (haemolysis), resulting in a low haemoglobin concentration (anaemia)

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5
Q

Several inherited conditions cause the red blood cells to be more fragile and break down faster than normal, leading to..

A

Chronic haemolytic anaemia

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6
Q

Inherited conditions that can cause chronic haemolytic anaemia

A

Hereditary spherocytosis
Hereditary elliptocytosis
Thalassaemia
Sickle cell anaemia
G6PD deficiency

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7
Q

The features that act as a result of the destruction of red blood cells are…

A

Anaemia
Splenomegaly
Jaundice

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8
Q

Ix for Haemolytic anaemia

A

Full blood count shows a normocytic anaemia

Blood film shows schistocytes (fragments of red blood cells)

Direct Coombs test is positive in autoimmune haemolytic anaemia (not in other types)

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9
Q

What is the most common type of haemolytic anaemia?

A

Hereditary spherocytosis

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10
Q

Hereditary spherocytosis is an autosomal dominant/recessive

A

Autosomal dominant

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11
Q

What is hereditary spherocytosis?

A

Fragile, sphere-shaped red blood cells that easily break down when passing through the spleen.

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12
Q

Anaemia, jaundice, gallstones and splenomegaly. A notable feature is aplastic crisis in the presence of the parvovirus

A

Hereditary Spherocytosis

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13
Q

Raised mean corpuscular haemoglobin concentration
Raised reticulocyte count
Spherocytes on a blood film

A

Hereditary Spherocytosis

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14
Q

Tx for Hereditary Spherocytosis

A

Folate supplementation

Blood transfusions when required and splenectomy

Gallbladder removal (cholecystectomy) if necessary

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15
Q

Hereditary elliptocytosis is similar to hereditary spherocytosis except that the red blood cells are ___________. It is also autosomal dominant. The presentation and management are the same as hereditary spherocytosis

A

Hereditary elliptocytosis is similar to hereditary spherocytosis except that the red blood cells are ellipse-shaped. It is also autosomal dominant. The presentation and management are the same as hereditary spherocytosis

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16
Q

G6PD deficiency is autosomal dominant/recessive

A

X-linked recessive

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17
Q

Acute episodes of haemolytic anaemia triggered by infections, drugs or fava beans

A

G6PD deficiency

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18
Q

Key medication triggers for G6PD deficiency

A

Ciprofloxacin, sulfonylureas (e.g., gliclazide) and sulfasalazine

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19
Q

Jaundice (often in the neonatal period), gallstones, anaemia, splenomegaly and Heinz bodies on a blood film

A

G6PD deficiency

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20
Q

Ix for G6PD deficiency

A

G6PD enzyme assay

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21
Q

What is autoimmune haemolytic anaemia?

A

When antibodies are created against the patient’s red blood cells. These antibodies lead to red blood cell destruction (haemolysis)

There are two types, warm and cold, based on the temperature at which the auto-antibodies destroy red blood cells

22
Q

Which type of autoimmune haemolytic anaemia is more common?

A

Warm autoimmune haemolytic anaemia - usually idiopathic

23
Q

Cold-reactive autoimmune haemolytic anaemia is also called..

A

Cold agglutinin disease

24
Q

Cold AIHA can be secondary..

A

Lymphoma, leukaemia, systemic lupus erythematosus and infections (e.g., mycoplasma, EBV, CMV and HIV)

25
Q

Mx of autoimmune haemolytic anaemia

A

Blood transfusions
Prednisolone
Rituximab (a monoclonal antibody against B cells)
Splenectomy

26
Q

What is alloimmune haemolytic anaemia?

A

Occurs due to foreign red blood cells or foreign antibodies

The two scenarios where this happens are transfusion reactions and haemolytic disease of the newborn

27
Q

What is Paroxysmal Nocturnal Haemoglobinuria?

A

Caused by a specific genetic mutation in the haematopoietic stem cells in the bone marrow

Results in a loss of the proteins on the surface of red blood cells that inhibit the complement cascade, allowing activation of the complement cascade on red blood cells and their destruction

28
Q

Red urine in the morning
Anaemia
Thrombosis (DVT, PE, hepatic vein thrombosis)
Smooth muscle dystonia (e.g., oesophageal spasm and erectile dysfunction)

A

Paroxysmal Nocturnal Haemoglobinuria

29
Q

The red urine caused by Paroxysmal Nocturnal Haemoglobinuria contains..

A

Hemoglobin and haemosiderin

30
Q

Mx for Paroxysmal Nocturnal Haemoglobinuria

A

Eculizumab (targets C5) or bone marrow transplantation

31
Q

What is Microangiopathic Haemolytic Anaemia?

A

Abnormal activation of the clotting system, with blood clots (thrombi) partially obstructing the small blood vessels and causing destruction of RBCs

32
Q

Microangiopathic haemolytic anaemia is usually secondary to an underlying condition, such as..

A

Haemolytic uraemic syndrome (HUS)
Disseminated intravascular coagulation (DIC)
Thrombotic thrombocytopenic purpura (TTP)
Systemic lupus erythematosus (SLE)
Cancer

33
Q

_________ are a key finding on the blood film in patients with microangiopathic haemolytic anaemia

A

Schistocytes

34
Q

Haemolytic anaemia is a key complication of prosthetic heart valves. It occurs in both ____________ and ____________ replacements

A

Haemolytic anaemia is a key complication of prosthetic heart valves. It occurs in both bioprosthetic and metallic valve replacement

35
Q

Mx of Prosthetic Valve Haemolysis

A

Monitoring
Oral iron and folic acid supplementation
Blood transfusions if severe
Revision surgery may be required in severe cases

36
Q

What are the consequences of haemolysis

A

Erythroid hyperplasia (increased bone
marrow red cell production)

Excess red cell breakdown products eg billirubin (clinical features differ by aetiology and site of red cell breakdown)

37
Q

T or F: Retics are diagnostic of
haemolysis- response to bleeding

A

False

38
Q

Define Extravascular cell destruction

A

Taken up by reticuloendothelial system (spleen and liver predominantly)

39
Q

Define Intravascular cell destruction

A

Red cells destroyed within the circulation

40
Q

Intravascular/Extravascular cell destruction is the most common one

A

Extravascular

41
Q

What is Extravascular cell destruction?

A

Unconjugated bilrubinaemia
* Jaundice
* Gall stones
Urobilinogenuria
Normal products in excess

42
Q

What is Intravascular cell destruction?

A

Red cells are destroyed in the circulation spilling their contents
Abnormal products

43
Q

Haemoglobinaemia
Methaemalbuminaemia
Haemoglobinuria
Haemosiderinuria

A

Intravascular cell destruction

44
Q

T or F: Intravascular cell destruction may be life threatening

A

True

45
Q

What causes intravascular cell destruction

A

Mismatched blood transfusion
G6PD deficiency
Red cell fragmentation: heart valves, TTP, DIC, HUS
Paroxysmal nocturnal haemoglobinuria
Cold autoimmune haemolytic anaemia

46
Q

What causes extravascular cell destruction

A

Haemoglobinopathies
Hereditary spherocytosis
Haemolytic disease of newborn
Warm autoimmune haemolytic anaemia

47
Q

Pathophysiology of haemolytic anaemia

A

Free haemoglobin is released which then binds to haptoglobin. As haptoglobin becomes saturated, haemoglobin binds to albumin forming methaemalbumin (detected by Schumm’s test)

Free haemoglobin is excreted in the urine as haemoglobinuria, haemosiderinuria

48
Q

Other than intra and extravascular, what are the other classification by site of red cell defect?

A

Premature destruction of normal red cells
(immune or mechanical)
Abnormal cell membrane
Abnormal red cell metabolism
Abnormal haemoglobin

49
Q

What causes warm autoimmune haemolysis?

A

Idiopathic (commonest)
Autoimmune disorders (SLE)
Lymphoproliferative disorders (CLL)
Drugs (penicillins, etc)
Infections

50
Q

What causes cold autoimmune haemolysis?

A

Idiopathic
Infections (EBV, mycoplasma)
Lymphoproliferative disorders

51
Q

What causes abnormal cell membranes?

A

Liver Disease (Zieve’s Syndrome)
Vitamin E deficiency
Paroxysmal Nocturnal Haemoglobinuria

52
Q

How can abnormal cell metabolism cause red cell defect?

A

Failure to cope with oxidant stress (G6PD deficiency)

Failure to generate ATP: metabolic processes fail

Even the metabolic pathways of normal cells if sufficiently stressed e.g.by dapsone or salazopyrin can get oxidative damage

3MB Haematology (23 decks)

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