What is Pernicious anaemia?

an autoimmune disorder affecting the gastric mucosa that results in vitamin B12 deficiency

What patient groups is Pernicious anaemia most common?

common in females (F:M = 1.6:1) and typically develops in middle to old age

What are the main clinical features of Pernicious anaemia?

• anaemia features (lethargy, pallor, dyspnoea)
• neurological features
  • peripheral neuropathy: 'pins and needles', numbness. Typically symmetrical and affects the legs more than the arms
  • subacute combined degeneration of the spinal cord: progressive weakness, ataxia and paresthesias that may progress to spasticity and paraplegia
  • neuropsychiatric features: memory loss, poor concentration, confusion, depression, irritabiltiy
• other features
  • mild jaundice: combined with pallor results in a 'lemon tinge'
  • glossitis → sore tongue

What is the pathophysiology of Pernicious anaemia?

antibodies to intrinsic factor +/- gastric parietal cells

• intrinsic factor antibodies → bind to intrinsic factor blocking the vitamin B12 binding site
• gastric parietal cell antibodies → reduced acid production and atrophic gastritis. Reduced intrinsic factor production → reduced vitamin B12 absorption

What are the main associations of Pernicious anaemia?

• with other autoimmune disorders: thyroid disease, type 1 diabetes mellitus, Addison's, rheumatoid and vitiligo
• common if blood group A

What are the common complications of Pernicious anaemia?

increased risk of gastric cancer

What is seen on full blood count in Pernicious anaemia?

• macrocytic anaemia: macrocytosis may be absent in around of 30% of patients
• hypersegmented polymorphs on blood film
• low WCC and platelets may also be seen

What antibodies may be seen in Pernicious anaemia?

• anti intrinsic factor antibodies: sensitivity is only 50% but highly specific for pernicious anaemia (95-100%)
• anti gastric parietal cell antibodies in 90% but low specificity so often not useful clinically

What's the treatment for Pernicious anaemia?

B12 replacement