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MEH A > Session 5 Lecture 2 > Flashcards

Session 5 Lecture 2 Flashcards

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
Q

What is alpha-thalassaemia trait?

A

Deletion of two alpha globin gene

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26
Q

How does alpha thalassaemia train present?

A

Minimal or no anaemia and no physical signs - clinical findings are identical to those of beta-thalassaemia minor

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27
Q

What is haemoglobin H disease?

A

Deletion of three alpha globin genes therefore tetramers of beta-globin are formed.

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28
Q

How does haemoglobin H disease present?

A

There is moderately sever anaemia, resembling B-thalasaemia intermedia

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29
Q

What is hydrops fetalis?

A

Deletion of all four alpha globin genes

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30
Q

How does hyrops fetalis present in the foetus?

A

Excess of gamma-globin chains form tetramers that are unable to for deliver oxygen to tissues - usually intrauterine death

31
Q

How do you get sickle cell disease?

A

Results from mutation of glutamate to valine the b globin gene.

32
Q

What happens in sickle cell disease?

A

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
Q

How does sickle cell disease present?

A

Symptoms of anaemia usually mild

34
Q

What is another name for vitamin B12?

A

Cobalamin

35
Q

What is another name for vitamin B9?

A

Folate

36
Q

What are vitamin B12 and B9 required for?

A

DNA synthesis

37
Q

What does deficiency in vitamins B12 and folate lead to?

A

Megaloblastic anaemia

38
Q

What happens in megaloblastic anaemia?

A

The red cell precursor cells are unable to synthesise DNA and divide

39
Q

Why is megaloblastic anaemia so named?

A

Since nuclear maturation and cell division lag behind cytoplasm development, large “mega” partially replicated red blood cel precursor are released into bloodstream

40
Q

What do cells of megaloblastic anaemia look like?

A

Large nuclei and open chromatin

41
Q

What happens to folate once it is absorbed?

A

It is converted to tetrahydrofolate (FH4)

42
Q

What happens to tetrahydrofolate?

A

Enters the portal circulation and much of this is taken up by the liver as a store. Other is used in metabolism

43
Q

What is the role of tetrahydrofolate in metabolism?

A

It acts as a one-carbon carrier, accepting carbon from serine, glycine etc. Therefore forms a one-carbon pool

44
Q

What is a one-carbon pool?

A

This is a collection of the various one carbon forms of FH4.

45
Q

Give examples of some recipient reactions from this one-carbon pool?

A

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
Q

What effects can folate have in pregnant women?

A

Can result in neural tube defects in the developing foetus

47
Q

How is vitamin B12 obtained?

A

Only obtained from a food or animal origin

48
Q

What first happens to the B12 in the body?

A

It forms a complex with proteins called haptocorrins

49
Q

What happens to the haptocorrin B12 complex?

A

Digested by pancreatic proteases in the small intestine hence release B12 which then binds to instrinsic factor

50
Q

What happens if you have a deficiency in the intrinsic factor?

A

You get pernicious anaemia because of lack of B12 absorption

51
Q

What happens when the B12 is internalised in the ileum?

A

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
Q

What happens to about half of the B12 ?

A

Liver takes it up and stores it - sufficient supply for 3-6 years

53
Q

What is vitamin B12 needed for?

A

Two metabolic reactions

54
Q

What is one of the metabolic reactions that vitamin B12 is responsible for?

A

Transfer of a methyl group from FH4 to homocysteine to form methionine

55
Q

What is functional folate deficiency?

A

lack of vitamin B12 ‘traps’ folate in the stable methyl FH4 form thereby preventing it from synthesising nucleotides for DNA.

56
Q

How do you get G6PDH deficiency?

A

X-linked recessive inborn error of metabolism

57
Q

What is the important of G6PDH ?

A

It is the rate limiting enzyme of the pentose phosphate pathway which supplies reducing energy by maintaining NADPH levels

58
Q

Whys is NADPH needed?

A

To protect against oxidative stress by maintaining levels of reduced glutathione.

59
Q

What are patients G6PDH deficiency at risk of?

A

Haemolytic anaemia in states of oxidative stress such as infection or exposure to certain chemicals or medications

60
Q

What can pyruvate kinase deficiency lead to?

A

Haemolytic anaemia

61
Q

What is the function of pyruvate kinase?

A

Catalysts the final step in glycolysis, transferring the phosphate from phosphenol pyruvate to ADP to form ATP

62
Q

What are myeloproliferative neoplasms?

A

Group of diseases of the bone marrow in which excess cells are produced

63
Q

How do myeloprolifertive neoplasms arise?

A

Arise from genetic mutations in the precursors of the myleoid lineage in the bone marrow

64
Q

What causes myeloproliferative neoplasms?

A

Point mutation in one copy of the JAK 2 gene (Janus kinase 2)

65
Q

What are the clinical features of myeloproliferative disorders?

A

Hypercellular bone marrow, cytogenetic abnormalities, acute leukaemia

66
Q

What is essential thrombocythaemia?

A

Overproduction of platelets by megakaryocytes

67
Q

What is polycythaemia Vera?

A

Characterised by overproduction of red blood cells

68
Q

What is myelofibrosis?

A

Characterised by replacement of the haemopoietic tissue by connective tissue leading to impairment of the generation of all blood cells (pancytopenia)

69
Q 
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 What is polycythaemia?
A

Disease state in which the volume percent of erythrocytes in the blood (haematocrit) exceeds 55%.

70
Q

What is the cause of polycythaemia?

A

Increase in the number of erythrocytes or a decrease in the plasma volume

71
Q

What is polycythaemia Vera?

A

This is a specific form of polycythaemia which arises from a myeloproliferative neoplasm in the bone marrow resulting in overproduction of erythrocytes

72
Q

Clinical features of polycythaemia Vera?

A

Thrombosis, haemorrhage, burning pain, pruritis, splenic discomfort, gout and arthritis

73
Q

What is the treatment for polycythaemia?

A

Treatment consists of phlebotomy to maintain the haemoatocrit below 45%. Aspirin used for anti-platelet effects

MEH A (19 decks)

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