Causes of Gastritis
The two primary causes of chronic gastritis are Helicobacter pylori infection—which is the most common etiology worldwide—and autoimmune mechanisms. 1
Primary Etiologies
Helicobacter pylori Infection
- H. pylori is the dominant cause of environmental gastritis globally and represents the most important determinant of chronic gastric inflammation. 2
- This bacterial infection typically occurs in childhood and leads to lifelong, aggressive inflammation that progressively destroys the gastric mucosa over years to decades. 3
- H. pylori-related atrophic gastritis characteristically shows an antral-predominant or pan-gastric distribution pattern. 4
- The infection remains one of the most common serious pandemic infections, with more than half of the global population potentially affected. 3
- In the United States, prevalence has declined due to improved sanitation and living standards, but disadvantaged subpopulations and immigrants from high-prevalence regions (Central and South America, Caribbean, Eastern Europe, Asia, India) maintain higher infection rates. 5
Autoimmune Gastritis
- Autoimmune mechanisms represent the second major cause of chronic gastritis, characterized by immune-mediated destruction of gastric parietal cells. 1
- This form presents with a corpus-predominant atrophy pattern that characteristically spares the antrum. 4
- Autoimmune gastritis can occur in all age groups and typically manifests with vitamin B12 deficiency and pernicious anemia. 6
- Serologic markers include anti-parietal cell antibodies (highly specific) and anti-intrinsic factor antibodies. 4
- Laboratory findings often reveal macrocytic anemia from B12 deficiency or microcytic anemia from iron deficiency. 4
Less Common Causes
Other Infectious Agents
- Helicobacter heilmannii infection is a rare cause of chronic gastritis, though of minor significance in a worldwide perspective. 7
Inflammatory Bowel Disease
- Crohn's disease can involve the stomach and cause chronic gastritis. 8
- Lymphocytic or collagenous gastroenteropathies represent rare inflammatory conditions causing chronic gastric inflammation. 6
Pathophysiologic Considerations
Role of Acid Secretion
- Individual variations in gastric acid secretion—potentially due to hereditary differences in parietal cell mass or hormonal sensitivity—modulate the topographic distribution of H. pylori colonization and subsequent gastritis patterns. 7
- In genuine hypersecretors, H. pylori colonization and gastritis may be limited to the antrum, while in hyposecretors, gastritis predominates in the corpus. 7
Environmental Factors
- The decline in H. pylori-related gastric cancer in Western countries was associated with improvements in food preservation (refrigeration replacing salt) and year-round availability of ascorbic acid-containing foods. 5
- These changes prevented progression from superficial gastritis to atrophic gastritis. 5
Clinical Pitfalls
A critical caveat: The presence of intestinal metaplasia on gastric histology virtually always indicates underlying atrophic gastritis, even when atrophy is not explicitly reported by the pathologist. 4 This represents a commonly missed diagnostic opportunity requiring coordination between gastroenterologists and pathologists. 1
All patients diagnosed with atrophic gastritis should be evaluated for H. pylori infection using non-serologic tests (stool antigen, urea-breath test, or biopsy-based methods) for both detection and post-treatment eradication confirmation. 4