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HAEMATOLOGY > MACROCYTIC ANAEMIA > Flashcards

MACROCYTIC ANAEMIA Flashcards

1
Q

What is the normal range for mean cell volume?

A

80-95 fl

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2
Q

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

A

Megaloblastic anaemia (right shift)

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3
Q

What processes are affected by folate or B12 deficiency?

A

DNA synthesis

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4
Q

What is the daily requirement of vitamin B12?

A

1 microgram

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5
Q

Where is vitamin B12 absorbed?

A

Ileum

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6
Q

What must be present for vitamin B12 to be absorbed?

A

Intrinsic factor

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7
Q

Where is intrinsic factor excreted?

A

Parietal cells of the stomach.

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8
Q

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

A

Pernicious anaemia

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9
Q

What is the underlying mechanism of pernicious anaemia?

A

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

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10
Q

Is pernicious anaemia more common in males or females?

A

Females

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11
Q

What is the peak age of onset for pernicious anaemia?

A

60

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12
Q

What diseases are associated with pernicious anaemia?

A 
Vitiligo - patchy whiteness of the skin
Myxoedema
Hashimoto's disease
Addison's disease
Hypoparathyroidism
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13
Q

What is the daily requirement of folate?

A

100-200 micrograms

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14
Q

Where is folate absorbed in the intestine?

A

Upper small intestine

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15
Q

How long do body stores of folate usually last for?

A

4 months

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16
Q

What disease is especially associated with folate deficiency?

A

Coeliac disease

17
Q

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

A

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

18
Q

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

A

Oval macrocytes
Hypersegmented neutrophil neuclei
Low white cell or platelet count

19
Q

What are the characteristics bone marrow features of megaloblastic anaemia?

A

Megaloblastic erythroblasts

Giant metamyelocytes

20
Q

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

A 
Raised unconjugated bilirubin
Raised serum lactic dehydrogenase
Low B12
Low folate
Raised serum homocysteine
Parietal cell antibodies
Intrinsic factor antibodies
21
Q

Why is jaundice associated with megaloblastic anaemia?

A

Increased destruction of the red cell precursors in the marrow

22
Q

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

A 
Neuropathy
Neural tube defects
Gonadal dysfunction
Epithelial changes - such as glossitis
Cardiovascular disease
23
Q

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

A

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

24
Q

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

A 
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
25
Q

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

A

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

26
Q

What are the causes of megaloblastic anaemia?

A 
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
27
Q

What is the medical treatment of vitamin B12 deficiency?

A

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

28
Q

What is the medical treatment of folate deficiency?

A

Folic acid 5 mg daily for 4 months

Those with severe haemolytic anaemia should continue to have this dose once a week.

29
Q

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

A

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

HAEMATOLOGY (17 decks)

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