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Week 3 - Phase 3 > Anaemia 2 > Flashcards

Anaemia 2 Flashcards

1
Q

Describe the structure of Haemoglobin?

A

Globin is made up of 4 chains: 2 alpha and 2 beta.

There is a haem on each chain.

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2
Q

What chromosome the beta and gamma globin chain gene cluster found?

A

Chromosome 11

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3
Q

What chromosome is the alpha globin gene cluster found?

A

Chromosome 16

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4
Q

What machinary in the cell produces globin chains?

A

Ribosomes

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5
Q

What is the Hb in embyological life made of?

A

Hb Gower 1, Gower 2 and Portland 1.

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6
Q

What would a problem with embryological Hb cause?

A

Miscarriage

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7
Q

In fetal life, what is the most abundant Hb and what is it made of?

A

HbF - made of 2 alpha chains and 2 gamma chains.

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8
Q

What happens if someone has a problem with a Hb alpha chain coding gene?

A

There is a problem mid-pregnancy

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9
Q

When is HbA made?

A

After 3 months of life.

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10
Q

When would problems with Hb beta chain genes arise?

A

3-6 months old.

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11
Q

What is HbA made of?

A

2 alpha and 2 beta chains.

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12
Q

Normally, how many alpha chain coding genes are there?

A

4 - two on each chromosome 16.

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13
Q

Normally, how many B-chain coding genes are there?

A

2 - one on each chromosome 11.

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14
Q

What regions is alpha and beta thalassiaemias most common?

A

Mediterranean and SE asia.

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15
Q

What is the result of missing one alpha chain gene?

A

mild macrocytosis and hypochromia

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16
Q

What would be the result of missing 2 alpha chain genes?

A

microcytosis, increased RBC’s, mild anaemia.

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17
Q

What would be the result of missing 3 alpha chain genes?

A

HbH disease, small mishapen RBC’s, significant anaemia.

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18
Q

What would be the result of missing 4 alpha chain genes?

A

Alpha thalassaemia major. Incompatible with life. Cant make HbF or HbA.

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19
Q

What is HbH disease?

A

RBC’s re pale, bizarre shapes.

Lack of alpha chains resulting in excess B chains joining together to make a tetramer.

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20
Q

What is Hb Barts?

A

Lack of alpha chains so gamma chains are made and join together to make a tetramer.

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21
Q

What is beta thalassaemia major?

A

Missing both B globin-chain genes.

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22
Q

How is beta thalassaemia major inherited?

A

Autosomal recessive.

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23
Q

Why is beta thalassaemia major compatible with life and alpha thalassaemia major isnt?

A

As HbF doesnt have any B chains. Only a problem after 3 months of life when they cant make HbA.

24
Q

What is the result on RBC’s in B-thalassaemia major?

A
  • Significant dyserythropoiesus as RBCs are poorly haemoglobinised and dont pass quality control mechanisms to get out of the BM.
25
Q

Why is splenomegaly seen in children with B-thalassaemia major?

A

AS it is a major site of RBC breakdown.

26
Q

What clinical features may be seen in B-thalassaemia major?

A
  • Splenomegaly.

- Maxillary prominence and thick skull due to bone undergoing erythropoiesis.

27
Q

What is the long-term complication of regular blood transfusion?

A

Significant impact on life expectancy if iron is not chelated due to iron overload.
NB: patients are not iron deficient!

28
Q

What is the mutation that causes sickle cell anaemia?

A

Single amino acid substitution (point mutation) on globin protein at position 6.
Glutamine to valine.

29
Q

Describe haemoglobin in sickle cell disease?

A

HbS is made.

This consists of 2 alpha chains and 2 Bs chains.

30
Q

What is the problem with HbS?

A

It sickles under stress such as hypoxia, dehydration, fever.
It forms fibrin structures and makes a sickle shaped RBC cell.
These RBC’s are rigid and cant bend through capillaries and can cause occlusion.

31
Q

Describe a sickle cell blood film?

A
  • few normal cells
  • can see sickle shaped RBC’s
  • Can see target cells
32
Q

What is the clinical result of sickle cell anaemia?

A
  • Reduced RBC survival (possibly 10 days)

- Vaso-occlusion due to blocked capaillaries and downstream tissue can become hypoxic and infarct.

33
Q

Describe possible complications of sickle cell anaemia in the;

  • brain
  • lungs
  • spleen
  • bones
  • kidneys
  • urogenital system
  • in pregnancy
  • eyes.
A

Brain: strokes or moya-moya (small vessels regrow post-infarction but later rupture or haemorrhage).
Lungs: Acute chest syndrome (small hypoxic areas cause pain, pulmonary hypertension and oedema).
Spleen: Can have a splenic infarction causing hyposplenism and need antibiotics and vaccines prophylactically.
Bones: Dactylitis (in children seen as swollen fingers due to infact of the metacarpals). Osteonecrosis in adults.
Kindeys: Infarction - renal failure.
Urogenital: Priapism (maintained erection).
Pregnancy: Foetal loss due to poor blood delivery.
Eyes: Retinopathy.

34
Q

How is a sickle cell crises managed?

A
  • prompt analgesia
  • Hydration
  • O2 therapy
  • Blood transfusion/RBC exchange
35
Q

What is haemolytic anaemia?

A

Premature breakdown of RBC’s before 120days.

RBC lifespan can be as short as 5 days, but if the BM doesn’t compensate, a haemolytic anaemia occurs.

36
Q

What are the 2 types of haemolytic anaemia?

A

Intravasular

Extravasular: In the macrophages of the RES (LIVER, SPLEEN, BONE MARROW).

37
Q

How does the bone marrow respond to haemolysis?

A

Marrow has a fantastic reserve and increases erythropoiesis and pushes out reticulocytes.

38
Q

How short does the RBC lifespan have to be until the bone marrow can’t compensate anymore?

A

<20days

39
Q

What LFT is derranged in haemolytic anaemia?

A

Uncongugated bilirubin is increased.

40
Q

What are the 3 kinds of congenital haemolytic anaemia?

A
  1. Abnormalities of RBC membrane (e.g. herititary spherocytosis)
  2. Haemoglobinopathies e.g. sickle cell or thalassaemia.
  3. Abnormalities in RBC enzymes (e.g. pyruvate kinase or glucose-6-phosphate dehydrogenase deficiency).
41
Q

Describe hereditary spherocytosis?

  • how is it inherited?
  • What is the problem?
  • blood film?
  • features?
  • treatment?
A
  • Autosomal dominant
  • Causes a defect in the RBC membrane proteins resulting in shape change and making them less deformable. They get trapped in the spleen and cause an extravasular haemolysis
  • RBC’s are polychromic (dark) and spherocytic (round).
  • Jaundice, splenomegaly
  • Treat with folate for increased erythropoiesis. If it doesnt correct then do splenoectomy and give prophylactic protection against bacterial infection.
42
Q

If someone has a splenectomy, what are the 3 main organisms you need to give prophylaxis for to reduce chances of infection?

A

Encapsulated organisms

  • pneumococcus
  • Meningococcus
  • Haemophilus.
43
Q

Describe how abnormalities in RBC enzymes can result in haemolytic anaemia? How are they inherited?

A

Pyruvate kinase deficiency

  • PK normally converys glucose to pyruvate
  • Decreased ATP causes decreased RBC survival
  • extravascular haemolytic anaemia
  • Autosomal recessive

Glucose-6-Phosphate Dehydrogenase Deficiency

  • Normally converts NADP to NADPH and the reducing power protects against oxidative stress.
  • Can get oxidative stress from fava beans and drugs such as aspirin.
  • Get very acute, episodic intravascular haemolysis
  • X-linked recessive.
44
Q

What are the 2 types of Acquired haemolytic anaemia?

A
  • Warm types and cold type. Named based on optimal binding temperature of autoantibodies to RBCs.
45
Q

What type of immunoglobulin mediates warm type/cold type acquired haemolytic anaemia?

A

warm: IgG
cold: IgM

46
Q

Infection by what organism can induce cold AIHA?

A

Myocoplasma pneumonia

47
Q

Which type of AIHA is linked to other autoimmune conditions?

A

Warm type

48
Q

What can cause warm AIHA?

A
  • Idiopathic
  • Drug-induced
  • Lymphoproliferativr disorders (NHL/CLL)
49
Q

Describe the blood film in warm AIHA?

A

Spherocytes
Polychromatic cells (reticulocytes)
Antibody coated red cells.

50
Q

Describe the 3 ways drug induced AIHA can occur?

A
  1. Drug binds to RBCs and acts as a hapten to increase immune response.
  2. Drug raises immune response to itself and reaction occurs in the blood. Compliment is recruited. Some can spill over onto RBCs causing haemolysis.
  3. Drug can stimulate antibodies against RBC.
51
Q

How is cold AHIA treated?

A

Self-warming.

52
Q

How do you treat warm AHIA?

A
  • stop any drugs
  • steroids (prednisalone)
  • Immunosuppression
  • Splenectomy to reduce haemolysis.
53
Q

What is haemolytic disease of the new born?

A

When a rhesus -ve mother produces rhesus +ve antibodies if the foetus is rhesus +ve.
More common in 2nd pregnancy.

54
Q

Describe the direct coombs test?

A
  • Blood sample is taken from a patient with immune mediated haemolytic anaemia where anibodies are attached to antigens on the RBC surface.
  • The patients washed RBCs aare incubated with anti-human antibodies.
  • The test is positive if RBCs agglutinate as the antihuman antibodies form links between RBC’s by binding to the human antibodies on the RBC’s.
55
Q

What conditions would the direct coombs test be positive in?

A

Haemolytic diseas of the newborn

AIHA

56
Q

Describe the indirect coombs test?

A
  • Patients serum is obtained containing antibodies (IG’s)
  • A donor blood sample is added to the tube of serum.
  • The patienrs Ig’s that target the donors RBCs will form anti-gen/anti-body complexes.
  • Anti-human immunoglobulins are added to the solution.
  • A positive result is when RBCs agglutinate because human Ig’s are attached to the RBCs.

This test is used before blood transfusion.

Week 3 - Phase 3 (3 decks)

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