Atrophic Gastritis

Chronic gastritis with loss of the specialised gastric glands (parietal and chief cells), replaced by fibrosis or by intestinal-type epithelium (intestinal metaplasia), producing low acid output and a raised risk of gastric cancer.

• Two main forms: environmental metaplastic atrophic gastritis (multifocal, antral and corpus, mostly from long-standing H. pylori infection, diet high in salt, smoking, alcohol) and autoimmune atrophic gastritis (corpus limited).
• Prevalence rises with age, affecting about 5 to 10% of adults in low risk areas and more than 30 to 50% of older adults in high risk areas; H. pylori infection is the main driver.
• Gastric cancer sequence: chronic gastritis, atrophy, intestinal metaplasia, low grade dysplasia, high grade dysplasia, adenocarcinoma; the annual risk of cancer is about 0.1 to 0.3% for atrophic gastritis or intestinal metaplasia, and higher with extensive disease, incomplete metaplasia, family history, or persistent infection.
• Mechanism: chronic inflammation causes gland loss and hypochlorhydria, which raises gastric pH, allows bacterial overgrowth and nitrosamine formation, and impairs iron and B12 absorption.

Often asymptomatic; or mild dyspepsia, early satiety, bloating, nausea.

• Anaemia (iron deficiency early; B12 deficiency with corpus involvement), glossitis, paraesthesia, weight loss.
• Increased risk of enteric infections, small bowel bacterial overgrowth and fractures.
• Differential diagnosis: autoimmune gastritis (corpus predominant), H. pylori non-atrophic gastritis, functional dyspepsia, gastric cancer, lymphoma, coeliac disease, chronic atrophic gastritis due to proton pump inhibitors (mimics pepsinogen changes).
• Complications: iron and B12 deficiency, dysplasia, gastric adenocarcinoma, type 1 gastric neuroendocrine tumours (in corpus atrophy with hypergastrinaemia), bacterial overgrowth, osteoporosis.

Upper endoscopy with narrow-band imaging or chromoendoscopy: pale mucosa with visible submucosal vessels, loss of rugal folds, patchy intestinal metaplasia (light blue crest or white opaque substance). Take five biopsies (two antrum, one incisura, two corpus) in separate pots. Histology gives the extent and severity of atrophy and metaplasia (complete or incomplete type), and dysplasia.

• Helicobacter pylori testing by histology, urea breath test or stool antigen (off proton pump inhibitors for 2 weeks and antibiotics for 4 weeks); serology if atrophy makes other tests falsely negative.
• Serum pepsinogen I (less than 70 micrograms/L) and pepsinogen I to II ratio (less than 3) indicate corpus atrophy; gastrin 17; gastrin raised in corpus atrophy.
• Blood tests: full blood count, ferritin, vitamin B12, folate, anti-parietal cell and anti-intrinsic factor antibodies (to detect an autoimmune cause).
• Biopsy and expert histology for any nodule, ulcer, polyp or irregular area.

Helicobacter pylori eradication for 14 days (it halts progression and may reduce the risk of cancer, mostly when given before dysplasia):

• Omeprazole 20 mg twice daily, amoxicillin 1 g twice daily and clarithromycin 500 mg twice daily (where clarithromycin resistance is less than 15%).
• Bismuth quadruple therapy: omeprazole 20 mg twice daily, bismuth subsalicylate 524 mg four times daily (or bismuth subcitrate 120 mg four times daily), tetracycline 500 mg four times daily and metronidazole 500 mg three to four times daily.
• Penicillin allergy: omeprazole 20 mg twice daily, bismuth subsalicylate 524 mg four times daily, tetracycline 500 mg four times daily and metronidazole 500 mg three to four times daily for 14 days. Test of cure at least 4 weeks after antibiotics and 2 weeks off the proton pump inhibitor.

• Vitamin B12 for corpus atrophy with deficiency:
  • Hydroxocobalamin 1 mg IM on alternate days for 2 weeks, then 1 mg every 2 to 3 months for life.
  • Or cyanocobalamin 1000 micrograms IM daily for 7 days, weekly for 4 weeks, then monthly.
  • Oral cyanocobalamin 1000 to 2000 micrograms daily is an alternative.
• Iron: ferrous sulfate 200 mg once daily or on alternate days for 3 months after haemoglobin normalises; ferric carboxymaltose 1000 mg IV once if oral iron fails.
• Lifestyle: stop smoking, reduce alcohol, reduce salt and salt-preserved food, eat fresh fruit and vegetables; avoid unnecessary long-term proton pump inhibitors (they worsen corpus atrophy in H. pylori infection).
• Endoscopic surveillance (the key to early cancer detection):
  • Extensive atrophy or intestinal metaplasia in antrum and corpus: endoscopy with biopsies every 3 years (every 1 to 2 years if there is a family history of gastric cancer, incomplete intestinal metaplasia, persistent H. pylori, or high-risk features such as extensive disease).
  • Mild antral-only atrophy without risk factors: surveillance is not routinely required after H. pylori eradication.
  • Low grade dysplasia: repeat endoscopy with expert review within 6 months, then every 6 to 12 months; endoscopic resection for visible lesions.
  • High grade dysplasia or early cancer: endoscopic mucosal or submucosal dissection, or surgery.
• Type 1 gastric neuroendocrine tumours: surveillance every 12 months when less than 10 mm, endoscopic resection for 10 mm or more, with somatostatin analogue or antrectomy for recurrent disease (evidence limited).
• Special groups:
  • Children: very rare; investigate autoimmune and H. pylori causes.
  • Pregnancy: defer eradication until after delivery, replace B12 and iron.
  • Elderly: focus on deficiency treatment, individualise surveillance by fitness and life expectancy.
  • Renal impairment: adjust metronidazole and tetracycline in severe disease; use doxycycline instead of tetracycline where appropriate.
  • Immunosuppression: check for cytomegalovirus and fungal causes.
• Red flags: weight loss, dysphagia, vomiting, haematemesis or melaena, new anaemia, abdominal mass, dysplasia on biopsy, family history of gastric cancer.
• Follow-up: test of cure for H. pylori at 4 to 8 weeks; B12 and haemoglobin every 6 to 12 months; endoscopy every 3 years, or every 1 to 2 years in high-risk patients; review of risk factors yearly.