Pernicious Anaemia Flashcards
what is pernicious anaemia?
autoimmune disorder affecting the gastric mucosa that results in vitamin B12 deficiency
Other causes of B12 deficiency
- atrophic gastritis (secondary to H. pylori infection)
- gastrectomy
- malnutrition (e.g. alcoholism)
In pernicious anaemia, what are the autoantibodies mounted against?
antibodies to intrinsic factor +/- gastric parietal cells
How do anti-intrinsic factor antibodies cause B12 deficiency?
antibodies bind to IF
=> blocking the vitamin B12 binding site
How do anti-gastric parietal cell antibodies cause B12 deficiency
reduced acid production and cause atrophic gastritis
What is B12 used for in the body?
production of blood cells
myelination of nerves
What are the 2 most common symptoms caused by B12 deficiency?
megaloblastic anaemia
neuropathy
Risk factors for pernicious anaemia
- females
- middle to old age
- other autoimmune disorders
- blood group A
Clinical features of B12 deficiency
anaemia:
- lethargy
- pallor
- dyspnoea
neurological features:
- ‘pins and needles’
- numbness
- usually symmetrical
- affects legs >arms
subacute combined degeneration of the spinal cord: - weakness
- ataxia
- paresthesias
(may progress to spasticity and paraplegia)
neuropsychiatric features:
- memory loss,
- confusion
- depression
glossitis → sore tongue
Investigations for pernicious anaemia
- full blood count for MCV
- Haematinics
- blood film (hypersegmented polymorphs)
antibodies:
- anti-IF Ab
- anti-gastric parietal cell Ab
Management of B12 deificiency in pernicious anaemia
vitamin B12 replacement
- hydroxocobalamin IM 3 monthly
- loading 3 injections per week for 2 weeks
- folic acid supplementation may also be required
Pernicious anaemia causes an increased risk of what type of cancer?
Gastric cancer
