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Peptic Ulcers (Duodenal (Causes (Others (Emotional stress, chronic anxiety…

- - - - 3 Major Mechanisms
        
        Decreased prostaglandins
        
        Endothelial effects (stasis -> ischemia)
        
        Direct toxic ion trapping: Unionized NSAIDs diffuse into epithelial lining cells -> dissociate into acidic ionized state -> free H+ ions are trapped inside epithelial cells -> disruption of oxidative phosphorylation, ATP production, and cell integrity.
    - - Chronic
        
        Non-atrophic gastritis: Bacteria evade destruction. Urease converts urea to NH3 + H2O (NH3 buffers luminal H+). Catalase inactivates mucosal H2O2 and inhibits MAC-mediated lysis (HP avoids immune destruction)
        
        Corpus predominant atrophic gastritis:
        
        Antral predominant gastritis:CagA+ + H. pylori -> cytotoxins and mucosal inflammation cause astral D-cell destruction -> decreased somatostatin production -> hypergastrinemia -> parietal cell hyperplasia -> increased HCl secretion
      - Acute
    - - Emotional stress, chronic anxiety, depression: Causes increased gastric acid secretion (mechanism not understood), increased ulcer complications (bleeding, perforation)
      - Idiopathic: Mainly in the elderly with comorbid conditions (CKD, COPD, alcoholic cirrhosis, hyperparathyroidism)
      - Tobacco: Decreases pancreatic HCO3- secretions and decreases mucosal PG production
  - - - Rapid urease test (high sensitivity and specificity): Mucosal tissue inoculated into a well containing urea and pH-sensitive dye.
        Bacterial urease converts urea into NH4+ and raises pH in well (red) Cons:You can get false-negative results during PPI/antibiotic Rx.
      - Fecal Ag test: Positive 3 weeks after infection and for life Notes:
        High sensitivity with lower specificity, Positive predictive value (< 50%), Useful to R/O HP infection when low pretest probability. Especially useful for childrenNotes: High sensitivity and specificity for current infection. Less false-negative results than urea breath test during PPI Rx. Proves eradication after antimicrobial therapy
      - Urea breath test: Pros: High sensitivity and specificity for current infection. Most cost effective test. Confirms eradication after antimicrobial therapy. Cons: False-negative results during PPI/antibiotic Rx
- - - - Acute
      - Chronic