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Year 2 > Thalassaemia > Flashcards

Thalassaemia Flashcards

1
Q

Normal Hb structure

A

Haem + 2 alpha + 2 Beta

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2
Q

Foetal Hb structure

A

Haem + 2 alpha + 2 gamma

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3
Q

Hb delta structure

A

Haem + 2 alpha + 2 delta chains

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4
Q

Percentage of normal Hb in the blood

A

97%

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5
Q

Percentage of HbA2 in blood

A

2%

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6
Q

Percentage of HbF in adult blood

A

1%

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7
Q

What are thalassaemias

A

Genetic disease of unbalanced Hb synthesis (no production of one global chain)

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8
Q

Consequence of imbalance in global chains

A

Cell damage and death of precursors in bone marrow -HAEMOLYSIS

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9
Q

What is Beta and Alpha thalassaemia

A

Beta - reduced B chain synthesis

Alpha - reduced A chain synthesis

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10
Q

What is the result of Beta thalassaemia having no B chains present

A

Excess alpha chains combine with delta and gamma chains

Increased HbA2 and HbF

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11
Q

How is Beta thalassaemia caused

A

Point mutations - porudicing unstable B-globins that can’t be used

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12
Q

What is the most common type of B-thalassaemia

A

B-thalassaemia minor - hetereozygous state

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13
Q

Symptoms of BT - minor

A

Asymptomatic

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14
Q

Is anaemia present in BT - nor

A

YEs but mild/almsot absent

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15
Q

Appearance of RBCs

A

Hypo chromic

MICROCYTIC

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16
Q

What can BT- minor be confused with

A

iron-deficiency anaemia

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17
Q

How can this be distinguished from iron-deficiency anaemia

A

Serum ferritin and iron levels should be normal

Hb electrophoresis shows raised HbA2 and HbF

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18
Q

What is BT- Intermedia

A

Symptomatic wit h MODERATE ANAEMIA - no transfusion required

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19
Q

Clinical features of BT - Intermedia

A 
Splenomegaly 
Bone deformities
Recurrent leg ulcers
Gallstones
Infections
20
Q

When does BT-major present

A

Children - homozygous

21
Q

Signs of BT-major

A
  1. Recurrent bacterial infections
  2. Severe anaemia from 3-6 months (when switch from gamma to beta chain usage should occur)
  3. Extramedullary haemtopoiesis
22
Q

What is Extramedullary haematopoiesis

A

Ineffective RBC production outside marrow = hepatosplenomegaly and bone expansion - thalassaemic face

23
Q

Treatment of BT- major

A

Transfusion

24
Q

Result of hypertrophy of ineffective bone marrow in BT-major

A

Bone abnormalities

25
Q

What would a skull x-ray in BT-major show

A

Hair on end sign - increased marrow activity

26
Q

Blood results for BT-major

A

Microcytic

27
Q

Blood films for BT-major

A

Large + small irregular hypo chromic RBCs

28
Q

Ferritin levels in BT-major

A

Normal

29
Q

How is B-thalassaemia diagnosed

A
  1. Hypochromic microcytic anaemia
  2. Raised reticulocyte
  3. Nucleated RBC in circulation

Haemoglobin electrophoresis

30
Q

How is Beta-thalassaemia treated

A

Every2-4 weeks life-long transfusion + suppress ineffective extra medullary haematopoiesis to allow normal growth

Iron-chelating agents

Ascorbic acid

Splenectomy

Bone marrow transplant

Folic acid

31
Q

What level should Hb be kept above

A

90g/L

32
Q

Name two iron-chelating agents

A

Oral DEFERIPRONE + SC DESDERRIOXAMINE

33
Q

Side-effects of iron-chelating agents

A

Pain
deafness,
cataracts
Retinal damage

34
Q

Why are iron-chelating agents needed

A

Stop iron overload

35
Q

Why do we decrease iron loading

A

During infusions

36
Q

Why do we give ascorbic acid

A

Increase urinary excretion of iron

37
Q

When do we do a splenectomy

A

If large spleen persists with increasing transfusion

38
Q

Complications from transfusion

A
  1. Progressive increase in body iron load
  2. Mainly deposited in the liver + spleen reulsting in liver fibrosis + cirrhosis
  3. Deposited in endocrine glands and heart = diabetes
39
Q

How are alpha-thalassaemias caused

A

Gene deletions

Gene for alpha-globing chains is duplicated on chromosome 16 + one alpha chain (more common) or both alpha-chain genes can be deleted

40
Q

Clinical presentation of alpha-thalassaemia (in four gene deletion- where both genes on both chromosomes occur)

A

No alpha chain synthesis

Hb BARTS present (4 gamma chains)

41
Q

What is the problem with Hb Barts

A

Can’t carry O2 so incompatible with life

Children are stillborn - pale, oedematous and have enormous livers + spleens)

42
Q

Consequence of 3 gene deletion in alpha-thalassaemia

A

Reduction in alpha chains = HbH increase (has four beta-chains)

43
Q

Symptoms of three gene deletion in alpha-thalaassaemia

A

MODERATE ANAEMIA
SPLENOMEGALY

(patient is not transfusion dependant)

44
Q

Two gene deletion alpha-thalassaemia signs

A

Microcytosis - mild anaemia

45
Q

One gene deletion alpha-thalassaemia signs

A

Normal blood

Year 2 (155 decks)

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