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Clinical Pathology > haemoglobinopathies > Flashcards

haemoglobinopathies Flashcards

1
Q

what shape are RBC

A

biconcave

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2
Q

what shape are RBC

A

biconcave

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3
Q

do RBC have nuclei

A

no

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4
Q

what is the function of RBC

A

transport oxygen which is found to haemoglobin

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5
Q

what molecule controls RBC levels and where is this molecule synthesised

A

Erythropoetein (EPO)

Kidney.

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6
Q

are the globin chains covalently bonded in haemoglobin

A

No.

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7
Q

what is the composition of haemoglobin in terms of the alpha and beta chains

A

2 alpha chains

2 beta chains

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8
Q

what is the function of glob in

A

protect harm from oxidation

renders the molecule soluble.

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9
Q

what is the composition of feral haemoglobin in terms of the alpha and gamma chains

A

2 alpha and 2 gamma chains

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10
Q

which 2 chromosomes control the glob in chains

A

chromosome 16- alpha

chromosome 11- gamma, delta and beta.

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11
Q

where is haemoglobin produced

3 places from inter to at birth

A

in the yolk sac -in utero
liver or spleen -10-12 weeks development in utero
bone marrow- end of gestation

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12
Q

define haemoglobinopathies

A

changes in globin genes or their expression leads to disease.

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13
Q

2 main types of haemoglobinpathies

A

structural-sickle cell (base substitution)

Thalassaemia- change in globin gene expression leads to reduced rate of synthesis of NORMAL globin chains.

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14
Q

plasma volume expands by how much in pregnancy

A

50%

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15
Q

red cell mass expands by how much in pregnancy

A

25%

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16
Q

what is defined as anaemia in the 1st and 3rd trimester

A
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17
Q

what is defined as anaemia in the second trimester

A
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18
Q

what happens to the number of white blood cells in pregnancy

A

Leukocytosis- increase in WBC

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19
Q

what happens to the platelet count during pregnancy

A

thrombocytopenia

platelet count is low- below the normal level but this is a physiological process.

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20
Q

causes of thrombocyopenia in pregnancy

A

production failure- severe folate deficiency.

Consumptive- gestational, pre-eclampsia and HELLP syndrome, AFLP, DIC e.g. in abruption TTP/HUS.

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21
Q

what makes pregnancy a prothrombotic state

A 
platelet activation
increase in procoagulant factors
reduction in natural anticoagulants.
reduction in fibrinolysis
rise in markers of thrombin generation
coagulation factors
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22
Q

how are haemoglobinopathies diagnosed/ detected.

A

Electrophoresis- for structural abnormalities.
Isoelectric focusing
High performance liquid chromatography.
Oxygen dissociation curve (p50, high affinity)
DNA analysis (genetic counseling, prenatal Dx)
Mass spectrometry
Kleihauer testing, Supravital staining, Sickle solubility

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23
Q

what is the substation which occurs in sickle cell anaemia

A

valine substituted for glutamine at postion 6 on B globin chain

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24
Q

why is the presentation of sickle cell only present 6 months after birth

A

foetal haemoglobin is present until 6 months after birth.

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25
Q

when do symptoms of sickle cell anaemia become evident

A

when extreme hypoxia/dehydration (eg very bad anaesthetia, flying unpressurised military aircraft)

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26
Q

acute complications of sickle cell disease.

A

Vaso-occlusicve crisis- hands and feet (dactylitis), chest syndrome, abdominal pain (mesenteric), bones (long bones, ribs, sin, brain, priapism-painful erection).
Septicaemia.
Aplastic crisis.
Sequestration crisis (spleen, liver).

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27
Q

chronic complications of sickle cell anaemia

A

Hyposplenism - due to infarction and atrophy of spleen, increased risk of infection.
Renal disease: medullary infarction with papillary necrosis. Tubular damage - can’t concentrate urine (bed-wetting at night). Glomerular – chronic renal failure/dialysis
Avascular necrosis (AVN) –femoral/humeral heads- need replacement, life long peniciclin.
Leg ulcers, osteomyelitis, gall stones, retinopathy, cardiac, respiratory

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28
Q

treatment for sickle cell anaemia.

A

Penicillin etc from 6 months

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29
Q

treatment for vaso-oclussion in sickle cell anaemia

A

analgesia (usually opiates), hydration (to maintain red cell water)

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30
Q

why is blood transfused in sickle cell anaemia.

A

Top up: splenic sequestration, aplastic crisis, pre-operative, acute chest crisis (usually when Hb

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31
Q

what is the function of Hydroxycarbamide

A

Increases Hb F

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32
Q

how do you cure sickle cell anaemia

A

Bone Marrow Transplant from normal donor

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33
Q

how can sickle cell be prevented

A

genetic counselling/prenatal diagnosis, avoiding precipitants

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34
Q

how many forms of thalasemia are there

A

4

α, β, δβ and γδβ

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35
Q

what is Hb harts

A

consists of four gamma chains. It is moderately insoluble, and therefore accumulates in the red blood cells

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36
Q

why is little oxygen delivered to tissues when you have Hb harts

A

It has an extremely high affinity for oxygen,

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37
Q

HbA thalassemia is more severe than B

A

foetal haemoglobin requires alpha but not b chains.

38
Q

do RBC have nuclei

A

no

39
Q

what is the function of RBC

A

transport oxygen which is found to haemoglobin

40
Q

what molecule controls RBC levels and where is this molecule synthesised

A

Erythropoetein (EPO)

Kidney.

41
Q

are the globin chains covalently bonded in haemoglobin

A

No.

42
Q

what is the composition of haemoglobin in terms of the alpha and beta chains

A

2 alpha chains

2 beta chains

43
Q

what is the function of glob in

A

protect harm from oxidation

renders the molecule soluble.

44
Q

what is the composition of feral haemoglobin in terms of the alpha and gamma chains

A

2 alpha and 2 gamma chains

45
Q

which 2 chromosomes control the glob in chains

A

chromosome 16- alpha

chromosome 11- gamma, delta and beta.

46
Q

where is haemoglobin produced

3 places from inter to at birth

A

in the yolk sac -in utero
liver or spleen -10-12 weeks development in utero
bone marrow- end of gestation

47
Q

define haemoglobinopathies

A

changes in globin genes or their expression leads to disease.

48
Q

2 main types of haemoglobinpathies

A

structural-sickle cell (base substitution)

Thalassaemia- change in globin gene expression leads to reduced rate of synthesis of NORMAL globin chains.

49
Q

plasma volume expands by how much in pregnancy

A

50%

50
Q

red cell mass expands by how much in pregnancy

A

25%

51
Q

what is defined as anaemia in the 1st and 3rd trimester

A
52
Q

what is defined as anaemia in the second trimester

A
53
Q

Endocrine complications of iron chelation.

A

Growth and development, screening for glucose intolerance, hypothyroidism and hypoparathyroidism.

54
Q

liver complications of iron chelation

A

LFT, ferritin, Hep Serology, MRI. Hepatologist if established disease

55
Q

causes of thrombocyopenia in pregnancy

A

production failure- severe folate deficiency.

Consumptive- gestational, pre-eclampsia and HELLP syndrome, AFLP, DIC e.g. in abruption TTP/HUS.

56
Q

what makes pregnancy a prothrombotic state

A 
platelet activation
increase in procoagulant factors
reduction in natural anticoagulants.
reduction in fibrinolysis
rise in markers of thrombin generation
coagulation factors
57
Q

how are haemoglobinopathies diagnosed/ detected.

A

Electrophoresis- for structural abnormalities.
Isoelectric focusing
High performance liquid chromatography.
Oxygen dissociation curve (p50, high affinity)
DNA analysis (genetic counseling, prenatal Dx)
Mass spectrometry
Kleihauer testing, Supravital staining, Sickle solubility

58
Q

what is the substation which occurs in sickle cell anaemia

A

valine substituted for glutamine at postion 6 on B globin chain

59
Q

why is the presentation of sickle cell only present 6 months after birth

A

foetal haemoglobin is present until 6 months after birth.

60
Q

when do symptoms of sickle cell anaemia become evident

A

when extreme hypoxia/dehydration (eg very bad anaesthetia, flying unpressurised military aircraft)

61
Q

acute complications of sickle cell disease.

A

Vaso-occlusicve crisis- hands and feet (dactylitis), chest syndrome, abdominal pain (mesenteric), bones (long bones, ribs, sin, brain, priapism-painful erection).
Septicaemia.
Aplastic crisis.
Sequestration crisis (spleen, liver).

62
Q

chronic complications of sickle cell anaemia

A

Hyposplenism - due to infarction and atrophy of spleen, increased risk of infection.
Renal disease: medullary infarction with papillary necrosis. Tubular damage - can’t concentrate urine (bed-wetting at night). Glomerular – chronic renal failure/dialysis
Avascular necrosis (AVN) –femoral/humeral heads- need replacement, life long peniciclin.
Leg ulcers, osteomyelitis, gall stones, retinopathy, cardiac, respiratory

63
Q

treatment for sickle cell anaemia.

A

Penicillin etc from 6 months

64
Q

treatment for vaso-oclussion in sickle cell anaemia

A

analgesia (usually opiates), hydration (to maintain red cell water)

65
Q

why is blood transfused in sickle cell anaemia.

A

Top up: splenic sequestration, aplastic crisis, pre-operative, acute chest crisis (usually when Hb

66
Q

what is the function of Hydroxycarbamide

A

Increases Hb F

67
Q

how do you cure sickle cell anaemia

A

Bone Marrow Transplant from normal donor

68
Q

how can sickle cell be prevented

A

genetic counselling/prenatal diagnosis, avoiding precipitants

69
Q

how many forms of thalasemia are there

A

4

α, β, δβ and γδβ

70
Q

what is Hb harts

A

consists of four gamma chains. It is moderately insoluble, and therefore accumulates in the red blood cells

71
Q

why is little oxygen delivered to tissues when you have Hb harts

A

It has an extremely high affinity for oxygen,

72
Q

HbA thalassemia is more severe than B

A

foetal haemoglobin requires alpha but not b chains.

73
Q

blood film b thalassaemia

A

abnormal with lots of nucleated red cells.

74
Q

clinical features of thalassaemia

A

severe anaemia
death from infection
Short stature and distorted limb growth due to premature closure of epiphyses in long bonesEnlarged liver and spleen “extramedullary haemopoiesis”

75
Q

thalassemia facies include

A

o Maxillary hypertrophy
o Abnormal dentition
o Frontal bossing due to expanded bone marrow

76
Q

pathology of B thalassemia

A

Increased marrow activity- skeletal deformities and stunted growth, increased iron absorption and organ damage (exacerbated by blood transfusion, Protein malnutrition.

Enlarged and overactive spleen- pooling of RBC and increased trans fusion requirement.

77
Q

classic X ray seen due to bone marrow expansion in thalassemia.

A

• X-ray showing classical “hair on end” skull due to widening of diploic cavities by marrow expansion

78
Q

trearment for B thlassemia.

A
  • Tranfusion- to maintain mean hb 12 g/dl (pre-transfusion Hb 9.5-10)
  • Suppresses marrow red cell production and prevents skeletal deformity and liver/spleen enlargement
79
Q

how often are transfusions for the first year of B thalassemia

A

3-4 weeks

80
Q

complications of transfusions in thalassemia include

A

iron overload
each unit of red cells contains 200-250mg Iron and the body has
no excretory mechanism for iron, therefore iron has to be removed

81
Q

complications of iron overload due to transfusion

A

gonads/hypothalamus – failure of puberty, growth failure
pancreas – diabetes
heart – dilated cardiomyopathy and heart failure
liver – cirrhosis.

82
Q

major complications of blood transfusion

A

Transmission of infection

Allo-immunisation- immune response to foreign antigens after exposure to genetically different cells or tissues

83
Q

Causes of death in thalassaemia

A

Most common is heart failure
Infection
Arrhythmias

84
Q

solution to prevent iron overload from transfusion

A

chelation therapy

85
Q

iron chelators include

A

Desferrioxamine

Deferiprone and Deferasirox

86
Q

what is the target ferrite level to aim for with iron chelators and why is the peel still higher than normal

A

1000-1500µg/L

If tried to reduce iron levels further would result in toxicity from iron chelators.

87
Q

Monitoring chelation

A

Ferritin (acute phase), liver biopsy, MRI (T2*)

88
Q

prevention of haemoglobinopathies

A

genetic counselling
anatenatal screening
neonatal screening
gene therapy

89
Q

Endocrine complications of blood transfusion.

A

Growth and development, screening for glucose intolerance, hypothyroidism and hypoparathyroidism.

90
Q

liver complications of blood transfusion

A

LFT, ferritin, Hep Serology, MRI. Hepatologist if established disease

91
Q

why does transfusion increase risk of infections

A

decreased CD4/8 ratio and defective neutrophil chemotaxis, increased virulence with excess iron (yersinia and DFO), line infections, transfusion transmitted infection.
Or
directly from donor blood

Clinical Pathology (45 decks)

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