Definition
Gastritis is the inflammation of the gastric mucosa (stomach lining), which can be either acute (sudden onset, often reversible) or chronic (long-term with progressive mucosal changes such as atrophy or intestinal metaplasia).
Etiology & Pathogenesis
Common Causes
- Drugs: NSAIDs and corticosteroids → inhibit prostaglandins → ↓ mucosal protection
- Alcohol, bile reflux, stress (e.g., ICU patients), radiation, chemotherapy
Infections
- H. pylori – most common in chronic gastritis
Other Causes
- Autoimmune gastritis (destruction of parietal cells)
- Bile reflux (e.g., in gallbladder dyskinesia)
- Secondary to systemic diseases: uremia, diabetes, CHF, hypercorticism
Classification
Acute Gastritis
- Sudden onset
- Often due to irritants (NSAIDs, alcohol)
- Mucosa can regenerate completely
Chronic Gastritis (Three types)
- Chronic autoimmune (atrophic) gastritis
- Autoimmune destruction of parietal cells → ↓ intrinsic factor → B12 deficiency
- Often associated with other autoimmune diseases
- Chronic H. pylori (superficial) gastritis
- Infection in antrum or entire stomach
- Most common chronic gastritis
- Inflammation may progress to ulcers, metaplasia, or cancer
- Chemical (reactive) gastritis
- Bile reflux, NSAIDs, alcohol
- Foveolar hyperplasia, mucosal edema