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Clinical Sciences > haemolytic anaemia > Flashcards

haemolytic anaemia Flashcards

1
Q

what is meant by ‘haemolysis’?

A
  • Premature attack and destruction of erythrocytes (<120
    days) – haemolysis
  • Detectable drop in the measured haemoglobin (anaemia)
  • Erythrocytes can either have an intrinsic defect
    (hereditary) or are otherwise healthy and attacked
    (acquired
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2
Q

how do we classify haemolytic anaemia by location?

A

Extravascular
Intravascular

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3
Q

what are the two causes of haemolytic anaemias

A
  • hereditary
  • acquired
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4
Q

what are the hereditary causes of haemolytic anaemia?

A

Problems with :
Membrane → Hereditary Spherocytosis (Hereditary elliptocytosis)

Metabolism→G6PD
(PKD and Embden- Meyerhof pathway defects)

Haemoglobinopathies → (Thalassemia
& Sickle Cell Disease)

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5
Q

what are the acquired causes of haemolytic anaemia?

A

Antibodies production causes RBC to be attached→ Autoimmune: Warm, mixed and cold

Alloimmune: Transfusion reaction/HDN

Drug Induced

Infections

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6
Q

Explain the normal Membrane structure and it’s importance

A

The erythrocyte membrane is asymmetrical
The lipid bilayer is anchored to a network of cytoskeletal proteins via transmembrane proteins such as:
- Band 3 (Most abundant)
- Phospholipid bilayer
- Alpha and Beta spectrin
- Ankyrin

•This network on the inner surface of membrane proteins provides shape, strength and flexibility to the membrane
(So they don’t get trapped/burst can deal with pressure)

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7
Q

Hereditary Spherocytosis is an example of what type of haemolysis

A

extravascular haemolysis

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8
Q

what type of membrane defect is caused in hereditary spherocytosis and what are the effects

A

> Autosomal dominant (75%)

> deficiency in Membrane proteins which can affect/ impair the overall interactions and network => loss of RBC membrane as it peels away which results in spherocytes

> Spherocytes Reduced SA:V ratio
Sequestered and destroyed in the
spleen (extravascular haemolysis) by macrophages

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9
Q

what are the symptoms of hereditary spherocytosis?

A
  • Jaundice (elevated levels of bilirubin
  • Anaemia (tired, pale)
  • enlarged spleen
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10
Q

what tests are run in the case of hereditary spherocytosis

A

Whole blood (K-EDTA) (purple)

Serum (SST) (biochem assay to look for markers) (yellow )

Urine

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11
Q

what is the transport time for a HS sample?

A

< 4 hurs

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12
Q

what temperature should HS sampke ve kept /stored at

A

4 °C

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13
Q

what does a HS FBC show

A
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14
Q

what will a blood film show for HS

A
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15
Q

what will a direct antiglobulin test show for HS

A

direct antiglobulin tests for the presence of antibodies coating RBC

no antibodies => -ve result

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16
Q

what biochemical test are performed for HS

A

Test- There are several causes of jaundice in neonates, so other causes should be excluded.
Result => elevated unconjugated bilirubin

serum aminotransferases
Test - Performed in the presence of jaundice.

Usually normal in HS but may be deranged with intercurrent viral infection.

Result=> usually normal

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17
Q

what will an EMA binding test show in HS

A
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18
Q

what treatment is provided in cases of HS

A

Folate Therapy
* Moderate-Severe HS
2. Splenectomy
* Effective at reducing haemolysis
* Increased risk of sepsis by encapsulated bacteria

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19
Q

what is the warm classification of Autoimmune Haemolytic Anaemia?

A
  • 80-90% of AIHA
  • Warm-reactive IgG antibodies that bind optimally at 37 °C
  • IgG with or without complement
  • Removed by MØ of the RES (extravascular = macrophages of reticular endometrium haemolysis)
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20
Q

what is the mixed classification of Autoimmune Haemolytic Anaemia?

A

5% of AIHA
Warm IgG and cold IgM

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21
Q

what is the cold classification of Autoimmune Haemolytic Anaemia?

A

10% of AIHA
- Cold-reactive IgM antibodies which Bind optimally at 4 °C
-IgM potent activators of complement
- Intravascular (due to the action of Igm and compliment (puncture holes in RBC)) & Extravascular (macrophages - RBC destruction)

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22
Q

what are the symptoms of warm AIHA?

A

Anaemia
Mild splenomegaly
Jaundice (RBC breakdown so more bilirubin present)
Secondary AIHA

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23
Q

what are the symptoms of cold AIHA?

A

Anaemia
Mild splenomegaly
Jaundice (RBC breakdown so more bilirubin present)
Raynaud’s Phenomenon

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24
Q

what specimen tests are carried out for AIHA

A

Whole blood (K-EDTA)
* Serum separation tube
* Rust top tube
* Urin

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25
Q

what is the transport time frame / storage temperature for sample

A

Transport <4h
* Refrigeration, 4 °C if necessary

26
Q

what will a FBC show for WARM AIHA

A
27
Q

what will a blood film show for WARM AIHA

A
28
Q

how is warm AIHA diagnosed using a direct antiglobulin test?

A

blood taken in in purple tube

29
Q

what will a cold AIHA blood film look like

A
30
Q

how is cold AIHA diagnosed using a direct antiglobulin test?

A
31
Q

what treatment is provided for warm AIHA

A
  1. Corticosteroids (e.g. prednisolone first-line treatment )
  2. Splenectomy – second line - damaged cells can continue to carry oxygen
  3. Monoclonal antibodies e.g. rituximab (anti-CD20)
  4. Treat the secondary cause
  5. Immunosuppressants
  6. Blood transfusion and/or Folic acid– severe case
32
Q

what treatment is provided in cold AIHA

A
  1. Stay warm! - avoid the cold
  2. Monoclonal antibodies e.g. rituximab
  3. Treat the secondary cause
  4. Blood transfusion and/or Folic acid– severe cases
33
Q

Define haemolytic anaemia of a newborn

A

A condition where the RBCs of the foetus or neonates are destroyed by immunoglobulin G (IgG) antibodies produced by the mother

34
Q

What are the two mechanisms of HDN?

A

Mechanism (1)- Antibody Adsorption
Mechanism (2)- Foetal-Maternal haemorrhage (FMH)

35
Q

describe the Antibody Adsorption mechanism

A

A foetus is immunised when the mother’s antibodies enter the baby’s circulation through the placenta.

The foetus absorbs the mother’s immunoglobulin towards the end of the pregnancy as a protective mechanism

Passage of maternal IgG can cause lysis of foetal cells

36
Q

What is Foetal-maternal Haemorrhage (FMH) in relation to first pregnancy

A

Rh - mother but father Rh + so child is Rh+

FMH occurs due to blood mixing during:
• Labor/delivery
• Rht blood being transfused to mum
• Ruptured ectopic pregnancy
• Placental abruption
• Abortion (spontaneous or elective)
• During 3rd trimester. absent cytotrophoblast of placenta

37
Q

How does the body respond to FMH first pregnancy

A

The mothers body’s recognises the antibodies as non self and become sensitised so antibodies are formed to fight Rh+ cells. In first pregnancy mother produces ITM antibodies which don’t cross the placenta wall so baby not harmed

38
Q

How does the body respond to FMH second pregnancy

A

In second pregnancy maternal IgG antibodies quickly form and recognise fetal cells as foreign and attack causing haemolysis as RBCs

39
Q

Pathologies if the second pregnancy

A

Antibodies from the mother Diffuse through the placenta into a fetus; an Attachment phase where antigens on the RBC attach to the antibodies then Agglutinationoccurs when RBC and agglutinant form a bond. These macrophages produce lytic enzymes to destroy RBCs causing Lysis. Phagocytosis FC receptor of immunoglobulin on spleen and macrophages recognises the FC portion of agglutinates causing haemolysis
** UCB (unconjugated bilirubin)** through macrophages being converted to CB(conjugated bilirubin) causing Extramedullary Hematopoiesis as bone morrow overworked

40
Q

Summarise the Pathogenesis

A
41
Q

what are the clinical presentations of HDN

A

Pale/yellow skin
Mild Jaundice
Urine discolouration
Splenomegaly
Hepatosplenomegaly
Hydrops fetalis
Kernicterus

42
Q

Kernicterus – (Bilirubin Encephalopathy)

A
43
Q

Discuss Hydrops Fetalis

A
44
Q

What laboratory Testing is done in HDN

A
  1. Maternal group antibody screen if anaemia is suspected then:
  2. FBC on baby
  3. ABO and Rh (D) typing of all babies born to a Rh(D)- mother.
  4. If baby group is Rh(D)- no further action.
  5. If baby group is Rh(D)+ a Kleihauer test is performed.
  6. Direct Agglutination Testing (DAT) - on foetal cells to detect bound antibody
45
Q

what is the timing of the screening

A
46
Q

what do the results for FBC And Blood Film show

A

Low HB
Low Hct
High reticulocytes (this may increase MCV)
High LDH
High unconjugated bilirubin
Low haptoglobin
Low albumin

47
Q

discuss a Direct Coombs test

A

Detects maternal anti-D antibodies that have already bound to fetal RBCs.
The anti-IgG binds “directly” to the maternal anti-D IgG that coats fetal RBCs in HDN.

48
Q

what is the Direct Coombs test used for

A

diagnoses HDN

49
Q

what test is used in the prevention of HDN

A

Indirect Coombs test

50
Q

Discuss the indirect Coombs test

A

Detects anti-D antibodies in the mother’s serum.
If these were to come into contact with fetal RBCs they would hemolyse them and hence cause HDN.

51
Q

describe the Laboratory Testing- Kleihauer – Betke Acid Elution Test

A
52
Q

what are the results of Kleihauer – Betke Acid Elution Test

A
53
Q

FMH Quantification by Flow Cytometry

A
54
Q

How Anti-D prophylaxis works-prevention in unsensitised mother

A
55
Q

ABO incompatibility in HDN

A

HDN occurs when a mother with blood group O becomes pregnant with a foetus with different blood types A, B or AB

ABO antibodies are naturally occurring antibodies that are clinically significant

ABO caused HDN commonly occurs but is less severe

56
Q

what are the Clinical features OF ABO HDN

A
57
Q

what are the Lab diagnosis of ABO HDN

A
58
Q

What are some of the other causes of HDN

A

Anti-E
(second most common, mild disease)

Anti-c
(third most common, leads to mild to severe)

Anti C and anti E (rare)

Antibody combination
(anti- C and anti- E occurring together can be severe)

Other antibodies
Kell system antibodies (uncommon causes)
Duffy, MNSs and Kidd system antibodies (rare causes)

Lewis and P system antibody no occurrence in HDN

59
Q

discuss HDN caused by anti-E

A

Anti-E is an antibody that can cause hemolytic disease of the newborn (HDN) when it is present in the mother’s blood and crosses the placenta to attack the baby’s red blood cells. The severity of HDN depends on the amount of anti-E antibody in the mother’s blood and the baby’s blood type.

The treatment for HDN depends on the severity of the condition. In mild cases, the baby may not require any treatment and the condition will resolve on its own. In more severe cases, the baby may require phototherapy, which involves exposing the baby’s skin to a special light that helps break down the bilirubin in the blood. In some cases, the baby may require a blood transfusion to replace the damaged red blood cells. In rare cases, the baby may require an exchange transfusion, which involves removing the baby’s blood and replacing it with donor blood.

60
Q

Treatment of HDNB

A

Clinical Sciences (8 decks)

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