Autoimmune Gastritis: Diagnosis and Management: Nature Reviews Gastroenterology & Hepatology | August 2026

Introduction:

Autoimmune gastritis (AIG) is a chronic immune-mediated disorder targeting the gastric oxyntic mucosa, resulting in progressive atrophy and impaired absorption of vitamin B12, iron, and other micronutrients. Once considered primarily a cause of pernicious anaemia, AIG is now recognized as a global disease with diverse gastrointestinal and extraintestinal manifestations.

Why was this study needed?

. AIG remains frequently underdiagnosed because its presentation can be subtle or multisystemic.

. The relationship between Helicobacter pylori infection and AIG remains incompletely understood.

. Newly recognized phenotypes, including potential AIG and seronegative AIG, challenge conventional diagnostic approaches.

. Uncertainty persists regarding gastric cancer risk and optimal endoscopic surveillance.

Results:

Current evidence suggests that AIG can develop through at least two pathogenic pathways: one potentially associated with H. pylori and another independent of infection. Progressive immune-mediated destruction of oxyntic glands leads to gastric atrophy and clinically important micronutrient deficiencies, particularly iron and vitamin B12 deficiency. Clinical presentation extends well beyond pernicious anaemia and can include gastrointestinal, neurological, haematological, and gynaecological manifestations.

The review also highlights potential AIG, representing patients with features suggesting evolving disease before established gastric atrophy, and seronegative AIG, in which conventional autoantibodies can be absent despite compatible disease. Although AIG is associated with gastric neoplasia, contemporary evidence suggests that the absolute risk of gastric adenocarcinoma may be relatively low in patients managed within structured endoscopic surveillance programs.

Clinical Impact:

Clinicians should consider AIG in unexplained iron or vitamin B12 deficiency and recognize that negative autoantibodies do not necessarily exclude the diagnosis. Diagnosis should integrate clinical, serological, biochemical, endoscopic, and histological findings. Long-term management requires correction and monitoring of micronutrient deficiencies together with appropriate endoscopic surveillance for gastric neoplasia.

Bottom Line:

Autoimmune gastritis is a heterogeneous, frequently overlooked disorder extending beyond pernicious anaemia; recognizing potential and seronegative disease and integrating micronutrient management with endoscopic surveillance are central to contemporary care.