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MEH A > Session 5 Lecture 2 > Flashcards

Session 5 Lecture 2 Flashcards

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1
Q

What is the definition of anaemia?

A

Haemoglobin concentration lower than the normal range

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2
Q

What does the normal range for haemoglobin vary with?

A

Age, sex and ethnicity

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3
Q

What is the normal haemoglobin range for an adult female?

A

115 - 165 g/L

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4
Q

What is the normal haemoglobin range for an adult male?

A

130 - 180 g/L

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5
Q

Describe some symptoms that might appear in acute onset anaemia?

A

Fatigue, dyspnoea, palpitations and headache

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6
Q

What symptoms might older patients experience when they are anaemic?

A

Might also experience angina and intermittent claudication

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7
Q

What are the clinical signs of anaemia?

A

Pallor, tachycardia and systolic murmur

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8
Q

Why might anaemia develop?

A

Due to abnormalities in the production, function or removal of red blood cells or to the excessive loss of blood.

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9
Q

Where are red blood cells made?

A

Bone marrow

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10
Q

What might cause abnormal erythropoiesis?

A

Exposure of the bone marrow to certain chemicals; benzene, chemotherapy, radiation, infection with parovirus or autoimmunity.

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11
Q

What is aplastic anaemia?

A

Inability of haemopoeitic stem cells to general mature blood cells.

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12
Q

What does aplastic anaemia result in?

A

Deficiency in all three blood cell types (pancytopenia) - rbc, wbc and platelets.

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13
Q

Give an example of how pathology outside the bone marrow causes a deficit in erythropoiesis?

A

Chronic kidney disease

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14
Q

What can cause iron deficiency?

A

Inc blood loss, inc requirement, dec dietary supply, dec absorption or anaemia of chronic disease

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15
Q

What is anaemia of chronic disease?

A

This is a lack of functional iron

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16
Q

What is anaemia of chronic disease associated with?

A

Chronic inflammatory conditions such as rheumatoid arthiritis, chronic infections and malignancy

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17
Q

What happens in anaemia of chronic disease?

A

Increase activity of macrophages reduces the lifespan of rbc and signalling through the erythropoitin receptor is blunted.

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18
Q

What disease form from mutations in the genes that encode the globin proteins therefore leading to anaemia?

A

Thalassaemia and sickle cell anaemia

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19
Q

What is the cause of thalassaemia?

A

Results from decreased or absent alpha or beta globin chain production resulting in excess in the other chain. This causes defective RBC therefore destroyed in bone marrow or spleen

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20
Q

What is B-thalassaemia major?

A

Homozygous

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21
Q

What is B-thalassaemia minor?

A

Heterozygous - one normal gene

Usually asymptommatic with mild anaemia

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22
Q

What is B-thalassaemia intermedia?

A

Genetically heterozygous, mild variants of homozygous

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23
Q

How does B-thalassaemia major present?

A

Severe transfusion-dependent anaemia that first manifests 6-9 months after birth

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24
Q

How does B-thalassaemia intermedia present?

A

Severe anaemia but not enough to require blood transfusions

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25
What is alpha-thalassaemia trait?
Deletion of two alpha globin gene
26
How does alpha thalassaemia train present?
Minimal or no anaemia and no physical signs - clinical findings are identical to those of beta-thalassaemia minor
27
What is haemoglobin H disease?
Deletion of three alpha globin genes therefore tetramers of beta-globin are formed.
28
How does haemoglobin H disease present?
There is moderately sever anaemia, resembling B-thalasaemia intermedia
29
What is hydrops fetalis?
Deletion of all four alpha globin genes
30
How does hyrops fetalis present in the foetus?
Excess of gamma-globin chains form tetramers that are unable to for deliver oxygen to tissues - usually intrauterine death
31
How do you get sickle cell disease?
Results from mutation of glutamate to valine the b globin gene.
32
What happens in sickle cell disease?
Sticky hydrophobic pocket in the b-globin protein allows deoxygenated haemoglobin to polymerise. This promotes cell suckling under low oxygen tension and eventually causes rbc membrane to lose elasticity
33
How does sickle cell disease present?
Symptoms of anaemia usually mild
34
What is another name for vitamin B12?
Cobalamin
35
What is another name for vitamin B9?
Folate
36
What are vitamin B12 and B9 required for?
DNA synthesis
37
What does deficiency in vitamins B12 and folate lead to?
Megaloblastic anaemia
38
What happens in megaloblastic anaemia?
The red cell precursor cells are unable to synthesise DNA and divide
39
Why is megaloblastic anaemia so named?
Since nuclear maturation and cell division lag behind cytoplasm development, large "mega" partially replicated red blood cel precursor are released into bloodstream
40
What do cells of megaloblastic anaemia look like?
Large nuclei and open chromatin
41
What happens to folate once it is absorbed?
It is converted to tetrahydrofolate (FH4)
42
What happens to tetrahydrofolate?
Enters the portal circulation and much of this is taken up by the liver as a store. Other is used in metabolism
43
What is the role of tetrahydrofolate in metabolism?
It acts as a one-carbon carrier, accepting carbon from serine, glycine etc. Therefore forms a one-carbon pool
44
What is a one-carbon pool?
This is a collection of the various one carbon forms of FH4.
45
Give examples of some recipient reactions from this one-carbon pool?
Includes the synthesis of the base thymidine required for DNA synthesis. Synthesis of the purine bases A and G needed for DNA and RNA synthesis
46
What effects can folate have in pregnant women?
Can result in neural tube defects in the developing foetus
47
How is vitamin B12 obtained?
Only obtained from a food or animal origin
48
What first happens to the B12 in the body?
It forms a complex with proteins called haptocorrins
49
What happens to the haptocorrin B12 complex?
Digested by pancreatic proteases in the small intestine hence release B12 which then binds to instrinsic factor
50
What happens if you have a deficiency in the intrinsic factor?
You get pernicious anaemia because of lack of B12 absorption
51
What happens when the B12 is internalised in the ileum?
It forms a complex with transcobalamin II and is released into he bloodstream for delivers to various tissues which have receptors for the transcobalamin II-B12 complex
52
What happens to about half of the B12 ?
Liver takes it up and stores it - sufficient supply for 3-6 years
53
What is vitamin B12 needed for?
Two metabolic reactions
54
What is one of the metabolic reactions that vitamin B12 is responsible for?
Transfer of a methyl group from FH4 to homocysteine to form methionine
55
What is functional folate deficiency?
lack of vitamin B12 'traps' folate in the stable methyl FH4 form thereby preventing it from synthesising nucleotides for DNA.
56
How do you get G6PDH deficiency?
X-linked recessive inborn error of metabolism
57
What is the important of G6PDH ?
It is the rate limiting enzyme of the pentose phosphate pathway which supplies reducing energy by maintaining NADPH levels
58
Whys is NADPH needed?
To protect against oxidative stress by maintaining levels of reduced glutathione.
59
What are patients G6PDH deficiency at risk of?
Haemolytic anaemia in states of oxidative stress such as infection or exposure to certain chemicals or medications
60
What can pyruvate kinase deficiency lead to?
Haemolytic anaemia
61
What is the function of pyruvate kinase?
Catalysts the final step in glycolysis, transferring the phosphate from phosphenol pyruvate to ADP to form ATP
62
What are myeloproliferative neoplasms?
Group of diseases of the bone marrow in which excess cells are produced
63
How do myeloprolifertive neoplasms arise?
Arise from genetic mutations in the precursors of the myleoid lineage in the bone marrow
64
What causes myeloproliferative neoplasms?
Point mutation in one copy of the JAK 2 gene (Janus kinase 2)
65
What are the clinical features of myeloproliferative disorders?
Hypercellular bone marrow, cytogenetic abnormalities, acute leukaemia
66
What is essential thrombocythaemia?
Overproduction of platelets by megakaryocytes
67
What is polycythaemia Vera?
Characterised by overproduction of red blood cells
68
What is myelofibrosis?
Characterised by replacement of the haemopoietic tissue by connective tissue leading to impairment of the generation of all blood cells (pancytopenia)
69
           What is polycythaemia?
Disease state in which the volume percent of erythrocytes in the blood (haematocrit) exceeds 55%.
70
What is the cause of polycythaemia?
Increase in the number of erythrocytes or a decrease in the plasma volume
71
What is polycythaemia Vera?
This is a specific form of polycythaemia which arises from a myeloproliferative neoplasm in the bone marrow resulting in overproduction of erythrocytes
72
Clinical features of polycythaemia Vera?
Thrombosis, haemorrhage, burning pain, pruritis, splenic discomfort, gout and arthritis
73
What is the treatment for polycythaemia?
Treatment consists of phlebotomy to maintain the haemoatocrit below 45%. Aspirin used for anti-platelet effects

MEH A (19 decks)

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