## Distinguishing Features: Duodenal vs Gastric Ulcer **Key Point:** Duodenal ulcers are characterised by increased gastric acid secretion and elevated basal acid output, whereas gastric ulcers typically occur in a setting of normal or reduced acid secretion. ### Pathophysiological Basis Duodenal ulcers arise in an acid-rich environment. Patients with duodenal ulcer disease have: - Higher basal acid output (BAO) - Increased maximal acid output (MAO) - Greater parietal cell mass - More aggressive acid-pepsin attack on the duodenal mucosa Gastric ulcers, by contrast, develop despite normal or even reduced acid secretion—the primary defect lies in mucosal defence (reduced mucus, bicarbonate, or blood flow). ### Comparison Table | Feature | Duodenal Ulcer | Gastric Ulcer | | --- | --- | --- | | **Acid secretion** | ↑ Increased (KEY) | Normal or ↓ decreased | | **Location** | First/second part of duodenum | Antrum, lesser curvature, incisura | | **Pathogenesis** | Acid hypersecretion + H. pylori | Mucosal defence failure | | **Intestinal metaplasia** | Rare in stomach | Common in gastric mucosa | | **Weight loss** | Uncommon | Common (alarm feature) | | **Malignancy risk** | Very low | Must exclude gastric cancer | **High-Yield:** The **increased acid secretion in duodenal ulcer** is the single most reliable discriminator and explains why duodenal ulcers respond dramatically to acid suppression (PPIs, H2-blockers). **Clinical Pearl:** A patient with a gastric ulcer presenting with weight loss and anaemia should raise suspicion for underlying gastric malignancy—gastric ulcers are not simply benign acid-related disease. ### Why Acid Secretion Matters Duodenal ulcers almost never occur without acid; they are an acid-dependent disease. Gastric ulcers can and do occur with normal acid levels because the primary problem is impaired mucosal protection (often from NSAIDs, H. pylori, or bile reflux). [cite:Harrison 21e Ch 297]
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.