Pernicious Anemia Lecture Notes

Overview

• Topic covered by Tom from zero2finals.com
• Focus on pernicious anemia, a cause of vitamin B12 deficiency anemia
• Related resources available on xerodefinals.com and Zero to Finals Medicine book

Causes of Vitamin B12 Deficiency

• Insufficient dietary intake of vitamin B12
• Pernicious anemia

Pathophysiology

• Parietal cells in the stomach produce intrinsic factor
• Intrinsic factor is essential for B12 absorption in the ileum
• Pernicious anemia: autoimmune condition where antibodies target parietal cells or intrinsic factor
• Lack of intrinsic factor leads to vitamin B12 deficiency

Symptoms of Vitamin B12 Deficiency

• Neurological symptoms:
  • Peripheral neuropathy with numbness or paresthesia (pins and needles)
  • Loss of vibration sense
  • Loss of proprioception
  • Visual changes
  • Mood and cognitive changes

Diagnosis

• Test for autoantibodies to diagnose pernicious anemia:
  1. Intrinsic factor antibodies (first-line investigation)
  2. Gastric parietal cell antibody (less helpful)

Management

• Dietary deficiency:
  • Treated with oral cyanocobalamin unless deficiency is severe
• Pernicious anemia:
  • Oral replacement is inadequate due to absorption issues
  • Treated with intramuscular hydroxycobalamin:
    • 1mg three times weekly for 2 weeks, then every 3 months
    • More intense regimes for neurological symptoms: 1mg daily until symptoms improve
• Folate deficiency:
  • Important to treat B12 deficiency before correcting folate deficiency
  • Incorrect treatment with folic acid can lead to subacute combined degeneration of the cord

Additional Resources

• Zero to Finals website with detailed notes, illustrations, questions
• Instagram account with daily questions
• Books, flashcards, and more educational materials
• Personal channel for insights on learning medicine

Conclusion

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