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Third year haematology lectures > Haemolytic anaemia > Flashcards

Haemolytic anaemia Flashcards

1
Q

front

A

back

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2
Q

What is the normal lifespan of an RBC?What is the cut off point in time for reduction in this lifespan where compensated haemolysis gives way to haemolytic anaemia?

A

120 daysBetween 15-120 days you rarely see anaemia

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3
Q

What are the two main classifications of sites of red cell destruction?Which one is pathological and which one is physiological?

A

Extravascular (physiological): Reticulo-endothelial system (bone marrow, liver and spleen)Intravascular (pathological): In bloodstream

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4
Q

What are the features of haemolytic anaemia?

A

Increased red cell production

  • increased reticulocyte count
  • erythroid hyperplasia

Increased red cell breakdown

  • increased: bilirubin, LDH (lactase dehydrogenase), urobilinogen
  • Reduced haptoglobin level
  • pigment gallstones

Haptoglobin(abbreviated asHp) is theproteinthat in humans is encoded by theHPgene.Inblood plasma, haptoglobin binds freehemoglobin(Hb) released fromerythrocyteswith highaffinityand thereby inhibits itsoxidativeactivity. The haptoglobin-hemoglobincomplexwill then be removed by thereticuloendothelial system(mostly thespleen). In clinical settings, the haptoglobulin assay is used to screen for and monitor intravascularhemolytic anemia. In intravascular hemolysis, free hemoglobin will be released into circulation and hence haptoglobin will bind the hemoglobin. This causes a decline in haptoglobin levels. Conversely, inextravascular hemolysisthereticuloendothelial system, especially splenic monocytes, phagocytose the erythrocytes and hemoglobin is relatively not released into circulation; however, excess hemolysis can release some hemoglobin causing haptoglobin levels to be decreased. Therefore, haptoglobin is not a reliable way to differentiate between intravascular and extravascularhemolysis.

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5
Q

How can causes of haemolysis be classified?Give examples.

A

Inherited

  • membrane
  • enzymes
  • haemoglobin

Acquired

  • Immune (allo or auto)
  • Non-immune
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6
Q

What is hereditary spherocytosis?What is its inheritance pattern?What causes it?How does it present clinically and on film?What is the treatment?

A 
An inherited disorder of spectrin
autosomal dominant
cells lose membrane during circulation
Variable anaemia and jaundice, microspherocytes on blood film, increased osmotic fragility
splenectomy if required
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7
Q

{{5 0 0.jpg}}What does this blood film show?

A

Spherocytes

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8
Q

What is hereditary elliptocytosis?What is its main inheritance pattern?Which disease is caused by homozygous disease?

A
  • A disease with similar, although less severe, clinical features
  • Mainly autosomal recessive
  • Pyropoikilocytosis
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9
Q

{{7 1 0.jpg}}What is this blood film showing?

A

Elliptocytes

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10
Q

What is osmotic fragility and how does it relate to haemolytic anaemia?

A

Osmotic fragility(OF) refers to the degree or proportion ofhemolysisthat occurs when a sample ofred blood cellsare subjected to osmotic stress by being placed in ahypotonicsolution. Osmotic fragility is affected by various factors, including membrane composition and integrity as well as the cells’ sizes or surface-area-to-volume ratios.[3][4][5]The osmotic fragility test is common inhematology, and is often performed to aid with diagnosis of diseases associated with RBC membrane abnormalities. Some diseases linked toincreasedOF includehereditary spherocytosisandhypernatremia, while some linked todecreasedOF include chronic liver disease, iron deficiency anemia, thalassemia, hyponatremia, polycythemia vera, and sickle cell anemia after splenectomy.[6]

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11
Q

What is the pentose phosphate pathway? What role does it play in haemolysis?

A

The production of NADPH protects red blood cells from oxidative damage.{{9 0 0.png}}

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12
Q

What is glucose-6-phosphate dehydrogenase deficiency?What are its clinical features?

A

G6PD is the only source of NADPH in red cellsClinical features

  • Anaemia after oxidative stress: drugs, fava beans, infection
  • Neonatal jaundice
  • Non-spherocytic haemolytic anaemia
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13
Q

Where is the greatest prevalence of G-6-PD deficiency?

A

Africa and south america

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14
Q

What is the inheritance pattern?Resistance to which disease is associated with G6PD deficiency?How is it diagnosed?How is it treated?

A

Inheritance is sex linkedMalariaEnzyme assayTreatment of symptoms

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15
Q

{{13 0 0.jpg}}What is this blood film indicative of?

A

G6PD deficiency (bite cell)

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16
Q

What is pyruvate kinase deficiency deficiency?How is it inherited?What are the clinical signs?How is it diagnosed?Treatment?

A

Failure to generate ATPAutosomal recessiveVariable anaemia, (4-10g/dl)- well tolerated, jaundice, gallstonesDiagnosis is made by enzyme assayTreatment is splenectomy if necessary

17
Q

Congenital haemoglobin disorders are often associated with Heinz bodies. What are Heinz bodies?

A

Heinz bodies(also referred to as “Heinz-Ehrlichbodies”) are inclusions within red blood cells composed of denatured hemoglobin.

18
Q

What amino acid change leads to sickle cell anaemia?What are the potential complications of sickle cell anaemia?

A

Glutamic acid to valine

Vaso-occlusive crises: stroke, splenic sequestration, sickle lung syndrome, priapism, haemolytic crisis, aplastic crisis

19
Q

Red cells coated in antibodies need an extra reagent to allow their detection. What test provides this?

A

Direct Coombs test uses the addition of anti-globulin to bind to and clump RBCs

20
Q

Autoimmunehemolytic anemiais caused by autoantibodies that react with RBCs at temperatures ≥ 37° C (warmantibodyhemolytic anemia) or < 37° C (coldagglutinin disease).Hemolysisis usually extravascular. The direct antiglobulin (direct Coombs) test establishes the diagnosis and may suggest the cause.
What are some examples of warm haemolytic anaemia?

A

IdiopathicSecondary to: SLE, lymphoma, CLL, drugsDue to IgG antibodies against red cells which lead to opsonisation of red cells in RE system

21
Q

What are the signs of warm AIHA?What are the investigative signs?What is treatement?

A

Clinical diagnosis: any age/sexhaemolysis of variable severityInvestigations: Direct coombs test posistive, spherocytosisTreatment: steroids, splenectomy, blood transfusion

22
Q

What are the causes of cold AIHA?Why is it cold?What are the investigations to diagnose?What are the treatments?

A

Primary
Secondary to infections such as mycoplasma, EBV

Antibody is IgM, lower affinity and only binds at cooler temperatures e.g. extremities
Red cell antigen is nearly always I or iInvestigations: DCT+ for complementTreatment: Keep warm, occasional cytotoxics

23
Q

Define alloimmune haemolytic anaemia.

A

Alloimmune hemolytic anemiaoccurs when the immune system produces antibody against foreign or non-self antigens. Examples include:Hemolytictransfusion reactions.Hemolyticdisease of the newborn (HDN)

24
Q

What is haemolytic disease of the newborn?

A

Maternal immune system recognises a foetal antigen as foreign. Antibody crosses the placenta.Usually RhD, also Kell, Rhesus C, duffy, Kidd.Sensitisation usually occurs at delivery therefore most problems present in second pregnancy.Anti-RhD after deliver is effective at reducing sensitisation.

25
Q

Which antibodies causes intravascular haemolysis following blood transfusion?

A

IgM

26
Q

What are 3 mechanisms by which drugs can cause immune haemolytic anaemia?What are 3 examples of drugs which can lead to a drug induced immune haemolytic anaemia?

A

Mechanisms

  • Ab to drug-red cell complex
  • Complement fixation due to deposition of Ag-Ab complexes
  • Ab to red cell itself

Examples

  • Penicillin
  • Quinidine
  • Methyldopa
27
Q

What are some causes of non-immune acquired haemolytic anaemia?

A

Red cell fragmentation syndromes

  • Microangiopathic HA
  • March haemoglobinuria
  • Cardiac valve haemolysis

Infection
Toxin
PNH (paroxysmal nocturnal haemoglobinuria)

28
Q

What is microangiopathic anaemia?What is it associated with?

A

Due to mechanical, intravascular haemolysis following pathological changes in small blood vessels.Associated with: haemolytic-uraemic syndrome, thrombotic thrombocytopoenic syndrome, pre-eclampsia, disseminated carcinoma, collagen vascular diseases

29
Q

What causes march and cardiac haemolysis?

A

March haemoglobinuria= follows walking or running on hard surfacesCardiac haemolysis= due to turbulence across heart valves

30
Q

What is a schistocyte?

A

Aschistocyteorschizocyte(fromGreekschistosfor “divided” orschizeinfor “to split”, andkytosfor “hollow” or “cell”) is afragmented partof ared blood cell. Schistocytes are typically irregularly shaped, jagged, and have two pointed ends.Severalmicroangiopathic diseases, includingdisseminated intravascular coagulationandthrombotic microangiopathies, generatefibrinstrands that sever red blood cells as they try to move past athrombus, creating schistocytes.Schistocytes are often seen in patients withhemolytic anemia. They are frequently a consequence of mechanicalartificial heart valvesandhemolytic uremic syndrome,thrombotic thrombocytopenic purpura, among other causes.

31
Q

Name two infections that can cause acquired haemolytic anaemia.Name two toxins that can cause haemolytic anaemia.

A

Malaria and clostridiaSulphonamide and dapsone

32
Q

What is the cause of PNH?How does PNH present?

How is it diagnosed?How is it treated?

A

Acquired disorder of red cell membrane. Due to mutation within PIG-A gene that leads to inability to produce GPI anchor for membrane proteins. Leads to haemolysis due to lack of complement inhibitorson red cell surface.
There appears to be selection for red cells with PIG-A mutation.
Diagnosis is made using Ham’s test- red cell lysis in presence of acidified complement.Treatment- Nil or anticoagulation

Third year haematology lectures (11 decks)

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