Chronic Gastritis

Long-standing inflammation of the gastric mucosa with a chronic inflammatory cell infiltrate, which may progress to glandular atrophy, intestinal metaplasia and dysplasia.

• Causes: Helicobacter pylori infection (the commonest, affecting about 50% of the world population and more than 70 to 80% of adults in many African countries; it causes antral predominant or pangastritis), autoimmune gastritis (corpus predominant), chemical injury (bile reflux, NSAIDs, alcohol), and less commonly Crohn disease, sarcoidosis, lymphocytic, collagenous and eosinophilic gastritis, radiation, and cytomegalovirus.
• Patterns: non-atrophic gastritis (mostly H. pylori), atrophic gastritis (multifocal from H. pylori, or corpus-limited autoimmune), and special forms.
• Natural history: peptic ulcer risk with antral predominant gastritis, and gastric cancer risk with extensive atrophy and intestinal metaplasia (annual progression to cancer about 0.1 to 0.3% in those with intestinal metaplasia).
• Mechanism: H. pylori colonises the mucus layer, releases urease, CagA and VacA, and induces neutrophilic and lymphocytic inflammation and cytokine release; acid output rises with antral disease and falls with corpus atrophy.

Most patients have no symptoms; some have epigastric discomfort, bloating, nausea, early satiety, belching, loss of appetite.

• Anaemia: iron deficiency (reduced acid and iron absorption, occult loss) and vitamin B12 deficiency (corpus atrophy), with fatigue, glossitis, paraesthesia.
• Examination is usually normal; pallor or neurological signs in B12 deficiency.
• Differential diagnosis: functional dyspepsia, peptic ulcer, gastro-oesophageal reflux, gastric cancer, gastric lymphoma, coeliac disease, biliary disease, pancreatic disease, gastroparesis.
• Complications: peptic ulcer, iron deficiency and B12 deficiency, intestinal metaplasia, dysplasia and gastric adenocarcinoma, mucosa-associated lymphoid tissue lymphoma (H. pylori related), type 1 gastric neuroendocrine tumours in corpus atrophy, and bleeding.

Upper endoscopy with biopsies: erythema, nodularity, erosions, atrophy with visible vessels, but the endoscopic appearance is not reliable; take five gastric biopsies (two from the antrum, one from the incisura, two from the corpus, in separate pots) for histology, with H. pylori staining and staging of atrophy and intestinal metaplasia.

• Helicobacter pylori testing: urea breath test or stool antigen (off proton pump inhibitors for 2 weeks and off antibiotics for 4 weeks), histology, rapid urease test; serology does not show current infection but is useful with atrophy or recent acid suppression.
• Blood tests: full blood count and film, ferritin and iron profile, vitamin B12 (less than 200 pg/mL or 148 pmol/L is low), folate, anti-parietal cell antibodies, anti-intrinsic factor antibodies, serum gastrin, pepsinogen I and II (low pepsinogen I or a pepsinogen I to II ratio less than 3 suggests corpus atrophy).
• Alarm features needing urgent endoscopy: age 55 years or more with new symptoms, weight loss, dysphagia, vomiting, bleeding, anaemia, family history of gastric cancer.

Helicobacter pylori eradication for 14 days when positive:

• Clarithromycin triple therapy (where clarithromycin resistance is less than 15%): omeprazole 20 mg twice daily, amoxicillin 1 g twice daily and clarithromycin 500 mg twice daily.
• Bismuth quadruple therapy (first choice where resistance is high or after treatment failure): 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: bismuth quadruple therapy: 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; if treatment fails use a regimen with different antibiotics (for example omeprazole 20 mg twice daily, amoxicillin 1 g twice daily and levofloxacin 500 mg daily for 14 days, or rifabutin 150 mg twice daily instead of levofloxacin).

```{=html} <!-- --> ``` - Symptom control: omeprazole 20 mg daily for 4 weeks, alginate-antacid 10 to 20 mL after meals and at bedtime; stop NSAIDs and alcohol; avoid smoking.

• Deficiency treatment:
  • Vitamin B12: hydroxocobalamin 1 mg IM on alternate days for 2 weeks then every 2 to 3 months for life (pernicious anaemia), or cyanocobalamin 1000 micrograms IM daily for 7 days, weekly for 4 weeks, then monthly; neurological involvement needs 1 mg IM on alternate days until no further improvement.
  • Iron: ferrous sulfate 200 mg once daily or on alternate days for 3 months after the haemoglobin normalises; intravenous ferric carboxymaltose 1000 mg (maximum 20 mg/kg) when oral iron fails, because acid loss and a proton pump inhibitor reduce absorption.
• Surveillance of atrophy and intestinal metaplasia: endoscopy with biopsies every 3 years for extensive or corpus involvement, and every 1 to 2 years with family history of gastric cancer, incomplete intestinal metaplasia, persistent H. pylori infection or dysplasia; dysplasia is treated by endoscopic mucosal or submucosal resection.
• Special groups: children (H. pylori treatment only for ulcer or persistent symptoms: omeprazole 1 mg/kg twice daily, amoxicillin 25 mg/kg twice daily and clarithromycin 7.5 mg/kg twice daily or metronidazole 10 mg/kg twice daily for 14 days); pregnancy (antacids and alginates, defer eradication until after delivery; avoid bismuth, tetracycline and clarithromycin); elderly (check B12 and iron, low threshold for endoscopy); renal impairment (reduce famotidine, avoid magnesium and aluminium antacids in severe disease); immunosuppression (test for cytomegalovirus and fungal causes).
• Red flags: weight loss, dysphagia, haematemesis or melaena, persistent vomiting, severe anaemia, neurological signs, new symptoms at age 55 years or more.
• Follow-up: test of cure at 4 to 8 weeks; B12 every 6 to 12 months after treatment; haemoglobin and ferritin at 3 months; endoscopic surveillance every 3 years, or every 1 to 2 years in high-risk patients.