Vitamin B12/folate deficiency

Question 1

Aetiology of vitamin B12 deficiency

Answer 1

Reduced absorption:
- Reduced intrinsic factor
- Gastric atrophy
Pernicious anaemia (Antibodies to IF or parietal cells)
Diseases of the small bowel
- Crohn’s
- Coeliac disease
- Surgical resection
Infections
- H. Pylori
- Giardia
- Fish tapeworm
- Surgical resection
Drugs
- Metformin
- PPIs e.g. omeprazole
- Oral contraceptive pill

Reduced intake: vegan

Question 2

Aetiology of folate deficiency

Answer 2

Reduced intake: alcoholics, elderly, anorexia
Reduced absorption: Jejunal disease e.g. coeliac, tropical sprue
Increased demand: pregnancy, lactation, malignancy, chronic inflammation or haemolysis
Drugs: phenytoin, trimethoprim, methotrexate

Question 3

Symptoms of vitamin B12/folate deficiency

Answer 3

Anaemia: SOB, pallor, fatigue

Symptoms of cause e.g. weight loss, diarrhoea, steatorrhoea, malnutrition, jaundice, hypothyroidism

Pernicious anaemia: jaundice, glossitis (red, sore), angular stomatitis, weight loss

Question 4

Signs of vitamin B12/folate deficiency

Answer 4

Anaemia: pallor, tachycardia
Pernicious anaemia: jaundice (lemon skin), glossitis (red, sore), angular stomatitis, weight loss
Vit B12:
- Peripheral neuropathy
- Ataxia
- Subacute combined degeneration of the spinal cord
- Optic atrophy
- Dementia

Question 5

Investigations for vitamin B12/folate deficiency

Answer 5

FBC: macrocytic anaemia (reduced Hb, raised MCV), megaloblastic anaemia → pancytopenia
Serum vitamin B12 and folate
anti-Parietal cell antibodies
Intrinsic factor
Blood film: macrocytes, macro-ovalocytes + hypersegmented neutrophils
LFTs: raised bilirubin
ESR
TFTs

Bone marrow biopsy: if myelodysplasia is suspected

Question 6

Management for vitamin B12/folate deficiency

Answer 6

Pernicious anaemia: IM hydroxycobalamin (3x weekly for 2 weeks, every 3 months for life)

Vitamin B12 deficiency: treated first if present (worsens neurological/subacute combined degeneration of the cord complications if second)

Folate deficiency: Oral folic acid 5mg daily (1–4 months or until recovery)

B12 - meat and dairy
Folate - green leafy vegetables, asparagus, broccoli, brown rice, nuts, yeast, chickpeas, peas

Question 7

Complications of macrocytic anaemia

Answer 7

Pernicious anaemia: Increased risk of gastric cancer
Folate deficiency and pregnancy: spina bifida

Question 8

Clinical features of subacute combined degeneration of the spinal cord

Answer 8

Due to degeneration of the dorsal columns

Paraesthesia, numbness and weakness of the legs, arms, trunk
Visual impairment
Mental state changes
Bilateral spastic paresis/paralysis
Diminished sensation (fine touch, proprioception, vibration)

+Babinksi’s sign
+ve Rhomberg