MACROCYTIC ANAEMIA

Question 1

What is the normal range for mean cell volume?

Answer 1

80-95 fl

Question 2

What type of macrocytic anaemia does folate or B12 deficiency cause?

Answer 2

Megaloblastic anaemia (right shift)

Question 3

What processes are affected by folate or B12 deficiency?

Answer 3

DNA synthesis

Question 4

What is the daily requirement of vitamin B12?

Answer 4

1 microgram

Question 5

Where is vitamin B12 absorbed?

Answer 5

Ileum

Question 6

What must be present for vitamin B12 to be absorbed?

Answer 6

Intrinsic factor

Question 7

Where is intrinsic factor excreted?

Answer 7

Parietal cells of the stomach.

Question 8

What is the most common cause of vitamin B12 deficiency in the UK?

Answer 8

Pernicious anaemia

Question 9

What is the underlying mechanism of pernicious anaemia?

Answer 9

Autoimmune gastritis where autoantibodies attack the parietal cells leading to a reduction in intrinsic factor.

Question 10

Is pernicious anaemia more common in males or females?

Answer 10

Females

Question 11

What is the peak age of onset for pernicious anaemia?

Answer 11

60

Question 12

What diseases are associated with pernicious anaemia?

Answer 12

Vitiligo - patchy whiteness of the skin
Myxoedema
Hashimoto's disease
Addison's disease
Hypoparathyroidism

Question 13

What is the daily requirement of folate?

Answer 13

100-200 micrograms

Question 14

Where is folate absorbed in the intestine?

Answer 14

Upper small intestine

Question 15

How long do body stores of folate usually last for?

Answer 15

4 months

Question 16

What disease is especially associated with folate deficiency?

Answer 16

Coeliac disease

Question 17

What are the clinical features of megaloblastic anaemia caused by a vitaman B12 or folate deficiency?

Answer 17

Pallor
Jaundice
Gradual onset
May present with signs of congestive heart failure

Question 18

What does the blood film of someone with anaemia related to vitamin B12 or folate deficiency look like?

Answer 18

Oval macrocytes
Hypersegmented neutrophil neuclei
Low white cell or platelet count

Question 19

What are the characteristics bone marrow features of megaloblastic anaemia?

Answer 19

Megaloblastic erythroblasts

Giant metamyelocytes

Question 20

Other than low Hb, what might a blood test of someone with megaloblastic anaemia show?

Answer 20

Raised unconjugated bilirubin
Raised serum lactic dehydrogenase
Low B12
Low folate
Raised serum homocysteine
Parietal cell antibodies
Intrinsic factor antibodies

Question 21

Why is jaundice associated with megaloblastic anaemia?

Answer 21

Increased destruction of the red cell precursors in the marrow

Question 22

Other than anaemia, what other effects are there from a vitamin B12 or folate deficiency?

Answer 22

Neuropathy
Neural tube defects
Gonadal dysfunction
Epithelial changes - such as glossitis
Cardiovascular disease

Question 23

What is the most common cause of raised MCV of red blood cells (macrocytosis) in the UK?

Answer 23

Alcohol - even quite small amounts and not necessarily associated with liver disease

Question 24

What are the causes of raised MCV of red blood cells?

Answer 24

Megaloblastic anaemia (B12 and folate)
Alcohol
Pregnancy and neonatal period
Myelodysplasia
Aplastic anaemia
Changes in plasma  protein (eg paraproteins associated with myeloma)
Drugs - hydroxyurea and azathioprine
Benign familial macrocytosis
Hypothyroidism

Question 25

Other than blood tests, what investigations would you do with someone who presented with megaloblastic anaemia?

Answer 25

Bone marrow examination Radioactive vitamin B12 absorption study - with and without intrinsic factor Endoscopy - to confirm atrophic gastritis or exclude gastric carcinoma

Question 26

What are the causes of megaloblastic anaemia?

Answer 26

``` Diet Pernicious anaemia Congenital intrinsic factor deficiency Gastrectomy Atrophic gastritis Stagnant loop Congenital selective malabsorption Ileal resection Crohn's Coeliac disease Jejunal resection Drugs - anticonvulsants, sulphasalazine ```

Question 27

What is the medical treatment of vitamin B12 deficiency?

Answer 27

Initial treatment is injections of hydroxycobalamin 1 mg every 3-4 days, followed by 4 injections a year for life.

Question 28

What is the medical treatment of folate deficiency?

Answer 28

Folic acid 5 mg daily for 4 months | Those with severe haemolytic anaemia should continue to have this dose once a week.

Question 29

What must you do before starting someone on treatment for folate deficiency?

Answer 29

Check vitmamin B12 levels as treatment may correct anaemia but allow neurological disease to develop.