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Key Features

  • A rare autoimmune disorder involving the fundic glands

    • Decreased intrinsic factor secretion

    • Consequent vitamin B12 malabsorption

  • Most patients have malabsorption secondary to chronic Helicobacter pylori infection that results in

    • Atrophic gastritis and achlorhydria

    • Small intestine bacterial overgrowth

    • Insufficient absorption of dietary vitamin B12

  • Fundic histology shows severe gland atrophy and intestinal metaplasia

Clinical Findings

  • Hypergastrinemia may induce hyperplasia of gastric enterochromaffin-like cells, development of small, multicentric carcinoid tumors in 5%

  • Risk of adenocarcinoma is increased threefold

  • Prevalence is 1–3%

Diagnosis

  • Endoscopy with biopsy

  • Achlorhydria leads to pronounced hypergastrinemia (> 1000 pg/mL)

  • Anti-intrinsic factor antibodies are present in 70%

  • Low serum vitamin B12 level

  • Megaloblastic (macrocytic) anemia

Treatment

  • One-time endoscopic screening for adenocarcinoma or carcinoids recommended

  • Patients with extensive atrophy and metaplasia involving the gastric antrum and body, dysplasia, or small carcinoids require periodic endoscopic surveillance

  • Vitamin B12 100 mcg intramuscularly daily for first week, weekly for first month, then monthly for life if B12 deficiency documented

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