Session 5-Anaemia, Vit B12 And Folate

Question 1

Why might anaemia develop?

Answer 1

Inability of body to deliver oxygen to tissues-either because not enough RBCs or not enough haemoglobin in RBCs

Question 2

Where does erythropoiesis occur?

Answer 2

Bone marrow

Question 3

Which system is involved in the removal of RBCs?

Answer 3

Reticulo-endothelial system

Question 4

What can lead to reduced erythropoiesis? (2)

Answer 4

1) empty bone marrow - unable to respond to stimulus from erythropoietin
2) marrow infiltrated by cancer cells or fibrous tissue so normal haemopoietic cells are reduced

Question 5

What happens in chronic kidney disease?

Answer 5

Kidney stops making erythropoietin

Question 6

In which conditions can anaemia of chronic disease (ACD) be seen?

Answer 6

• Rheumatoid arthritis
• Inflammatory bowel disease (ulcerative colitis or Crohn’s)
• Chronic infection eg TB
• Bronchiectasis (widening of bronchi)

Question 7

What are the features of anaemia of chronic disease?

Answer 7

1) iron stored in macrophages not released for use in bone marrow
2) circulating RBCs have reduced lifespan
3) marrow shows lack of response to erythropoietin
4) anaemia may be microcytic, normocytic or macrocytic

Question 8

What are the clinical signs of anaemia of chronic disease?

Answer 8

Increased CRP and ferritin

Question 9

What happens in myelodysplastic syndromes?

Answer 9

Production of abnormal clones of marrow stem cells - RBCs are large and defective so prematurely destroyed by reticuloendothelial system

Question 10

What can myelodysplastic syndromes lead to?

Answer 10

Progressive anaemia or pancytopenia

Acute leukaemia

Question 11

How are myelodysplastic syndromes treated?

Answer 11

Chronic transfusion of RBCs

Question 12

How can haemoglobin abnormalities lead to anaemia? (3)

Answer 12

1) lack of iron
2) deficiency in building blocks for DNA synthesis
3) mutations in genes that encode globin proteins

Question 13

What type of anaemia does vitamin B12/folate deficiency lead to?

Answer 13

Megaloblastic anaemia

Question 14

Complete the sentences:

Humans acquire vitamin B12 by eating foods of _________ origin, leading to excess of B12 in diet of _____ eaters. B12 is combined with glycoprotein ___________ ________ (IF) produced by ____________ cells in stomach. IF-B12 complex binds in _______, leading to absorption of B12 and destruction of IF. In portal blood, B12 is bound to plasma protein ________________ which delivers B12 to bone marrow and other tissues.

Answer 14

Animal 
Meat
Intrinsic factor
Parietal 
Ileum 
Transcobalamin

Question 15

What can a deficiency of B12 result from?

Answer 15

1) dietary deficiency
2) intrinsic factor (IF) - Pernicious anaemia
3) IF-B12 complex - disease of terminal ileum
4) transcobalamin deficiency

Question 16

What is Pernicious anaemia?

Answer 16

Autoimmune disease affecting gastric parietal cells causing lack of intrinsic factor

Question 17

Which foods are rich in folate?

Answer 17

Most foods: yeast, liver and leafy greens especially

Question 18

Where does folate absorption occur?

Answer 18

Duodenum and jejunum

Question 19

What are dietary folates converted to and what is it needed for?

Answer 19

Methyltetrahydrofolate (methylTHF) for DNA synthesis

Question 20

Why can folate deficiency occur?

Answer 20

Dietary deficiency 
Proximal small bowel disease eg coeliac disease
Crohn's disease 
drugs
Alcoholism 
Increased use eg pregnancy

Question 21

How do drugs lead to folate deficiency?

Answer 21

Dihydrofolate reductase enzyme eg Methotrexate leads to reduced methylTHF production

Question 22

What disease is vitamin B12 deficiency associated with and how does it do this?

Answer 22

Neurological disease

Focal demyelination affecting spinal cord, peripheral nerves and optic nerves (depression and dementia can also develop)

Question 23

What is thalassaemia?

Answer 23

Reduced rate of synthesis of normal alpha or beta globin chains

Question 24

What is sickle cell disease?

Answer 24

Synthesis of abnormal haemoglobin

Question 25

What are the different types of abnormal RBCs?

Answer 25

Spherocytes
Elliptocytes
Acanthocytes
Target cells

Question 26

Which RBC enzyme defects can lead to anaemia?

Answer 26

Glucose-6-phosphate dehydrogenase deficiency

Pyruvate kinase deficiency

Question 27

What is haemolytic anaemia?

Answer 27

Increased RBC destruction, either intravascular or extravascular

Question 28

What happens in autoimmune haemolytic anaemia?

Answer 28

Autoantibodies bind to red cell membrane proteins

Question 29

What are the two classifications of autoimmune haemolytic anaemia?

Answer 29

Warm autoimmune haemolytic anaemia, IgG maximally active at 37 degrees

Cold autoimmune haemolytic anaemia, IgM maximally active at 4 degrees

Question 30

What is a reticulocyte?

Answer 30

Immature RBC without nucleus

Question 31

What causes overproduction of cells in erythropoiesis?

Answer 31

Myeloproliferative disorders/neoplasms

Question 32

What are the different types of myeloproliferative neoplasms?

Answer 32

Thrombocythaemia
Polycythaemia
Myelofibrosis

Question 33

What is polycythaemia Vera?

Answer 33

Too many RBCs -> thick concentrated blood -> thrombosis

Question 34

What is erythrocytosis?

Answer 34

Increase in concentration of RBCs

Question 35

What is relative erythrocytosis?

Answer 35

Normal red cell mass, decreased plasma volume

Question 36

What is absolute erythrocytosis?

Answer 36

Increased red cell mass

Question 37

What is secondary erythrocytosis driven by?

Answer 37

Erythropoietin production

Question 38

Give examples of pathological erythropoietin production

Answer 38

Tumours eg hepatocellular carcinoma, renal cell cancer

Question 39

Give examples of physiologically appropriate erythropoietin production

Answer 39

Central hypoxia

Renal hypoxia