Can be due to either increased aggression/attack on stomach or impaired defences.

Acute - usually due to NSAIDs, alcohol or initial H. pylori infection Chronic - autoimmune (anti-parietal/intrinsic factor), H. pylori, chemical

Helicobacter pylori

  • Gram -ve spiral bacterium
  • Damages epithelium usually in antrum rather than body
  • Glandular atrophy and intestinal metaplasia