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Macrocytic anaemia Flashcards

1
Q

Causes of macrocytosis

A 
B12 or folate deficiency
Alcohol
Cytotoxics
Myelodysplasia 
Liver disease
Pregnancy
Hypothyroidism
Smoking
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2
Q

Vitamin B12 and folate are (blank blank) vitamins. They are found in…?
Are they destroyed by cooking?

A

Water soluble
B12 - meat, eggs, animal protein, not destroyed by cooking
Folate - liver, greens, yeast, destroyed by cooking

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3
Q

B12 is absorbed in?

A

Binds to intrinsic factor (produced by parietal cells of gastric mucosa) and is absorbed in the ileum epithelial cells

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4
Q

Folate is absorbed in?

A

Duodenum and proximal jejunum

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5
Q

What is a megaloblast?

A

A cell in which nuclear maturation is delayed compared with the cytoplasm

The cells are large, structurally abnormal, immature RBCs.

Vitamin B12 & folate are needed for DNA synthesis to convert homocysteine into methionine. If deficient, then DNA synthesis is impaired, cells fail to divide, leading to overlarge blood cells.

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6
Q

Effect of vitamin B12 or folate deficiency or inhibition on DNA synthesis

A

B12 and folate are needed for DNA synthesis to convert homocysteine into methionine
If deficient, then DNA synthesis is impaired, cells fail to divide, leading to overlarge blood cells.

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7
Q

Causes of vitamin B12 deficiency

A

Nutritional e.g. poor diet
Malabsorption e.g. pernicious anaemia (absence of intrinsic factor), surgical gastrectomy, ileal disease, drugs e.g. colchicine, metformin, PPIs

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8
Q

Causes of folate deficiency

A

• Nutritional – poor diet
• Malabsorption – coeliac, Crohn’s
• Excess utilization – pregnancy, lactation, haemolytic anaemias, malignancy, inflammatory disease
• Others – anticonvulsants (phenytoin, valproate), methotrexate, trimethoprim
+ LIVER DISEASE

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9
Q

Questions on history-taking to elucidate likely causes

A
  • Past medical history - e.g. inflammatory conditions, previous surgery
  • Drug history – hydroxycarbamide, phenytoin, valproate, methotrexate, trimethoprim
  • Social history - ask about diet, alcohol intake
  • Review of systems - symptoms of coeliac or Crohn’s (diarrhoea, constipation, abdominal pain, bloating, weight loss, fatigue), symptoms of malignancy (e.g. weight loss), history of pregnancy/breast-feeding
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10
Q

Symptoms of macrocytic anaemia

A 
Cognitive changes. 
Dyspnoea. 
Headache.
Indigestion.
Loss of appetite.
Palpitations.
Tachypnoea.
Visual disturbance. 
Weakness, lethargy.
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11
Q

Signs of macrocytic anaemia

A

Anorexia.
Angina (in older people).
Angular cheilosis.
Brown pigmentation affecting nail beds and skin creases (but not mucous membranes).
Congestive heart failure (in older people).
Episodic diarrhoea.
Glossitis — red smooth and shiny tongue, perhaps with ulcers.
Heart murmurs.
Liver enlargement.
Mild jaundice — a lemon-yellow tint.
Mild pyrexia.
Oropharyngeal ulceration.
Pallor of mucous membranes or nail beds.
Tachycardia.
Weight loss.

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12
Q

How much storage of B12 in the body?

A

2-5mg

About 2-5 years worth

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13
Q

How much storage of folate in the body?

A

10-12mg

About 4 months worth

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14
Q

Neurological complications associated with vitamin B12 def

A

Loss of cutaneous sensation.
Loss of mental and physical drive.
Muscle weakness.
Optic neuropathy.
Psychiatric disturbances – these range from mild neurosis to severe dementia.
Symmetrical neuropathy affecting the legs more than the arms — this usually presents with ataxia or paraesthesia.
Urinary or faecal incontinence.

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15
Q

Investigations

A

FBC - MCV (>100 femtolitres), haematocrit, Hb, WBC and platelets (reduced)
Blood film
Serum cobalamin and folate levels (+ anti-intrinsic factor abs)
LFTs
GGT
TFTs

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16
Q

Blood film findings

A

Hypersegmented neutrophils
Oval macrocytes
Circulating megaloblasts

17
Q

Management of folate deficiency anaemia

A

Oral folic acid 5 mg daily (usually for 4 months)
Check vitamin B12 levels — treatment can improve wellbeing, mask underlying B12 deficiency, and allow neurological disease to develop.
Give dietary advice
FBC and reticulocyte 7-10 days after starting treatment and after completion
Iron and folate levels after 8 weeks

18
Q

Dietary sources of folic acid

A 
Asparagus.
Broccoli.
Brown rice.
Brussels sprouts.
Chickpeas.
Peas.
19
Q

Management of vitamin B12 deficiency with NO neuro involvement

A

Initially - Vit B12 IM 3x a week for 2 weeks
If not diet related, give injection every 3 months for life.
If diet related - take tablets daily between meals, or have a twice-yearly injection.
Give dietary advice
FBC and reticulocyte 7-10 days after starting treatment
Iron and folate levels after 8 weeks

20
Q

Dietary sources of B12

A 
Eggs.
Fortified foods - e.g. cereal, bread 
Meat.
Milk and other dairy products.
Salmon and cod.
21
Q

Management of vitamin B12 deficiency with neuro involvement

A

Seek urgent specialist advice from a haematologist

CR (19 decks)

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