What is the treatment for autoimmune gastritis?

Treatment of Autoimmune Gastritis

The treatment of autoimmune gastritis centers on micronutrient replacement (iron and vitamin B-12), screening for and managing associated conditions (autoimmune thyroid disease and type 1 gastric neuroendocrine tumors), and endoscopic surveillance for gastric neoplasia. 1

Micronutrient Replacement Therapy

Iron Supplementation

• Iron deficiency occurs in up to 50% of patients with autoimmune gastritis and manifests earlier than vitamin B-12 deficiency, making it a priority for screening and treatment 2
• Iron deficiency develops due to reduced gastric acid secretion, which impairs absorption of dietary iron 2
• All patients with autoimmune gastritis should be evaluated for iron deficiency regardless of symptoms, particularly those with corpus-predominant disease 1, 2
• Iron stores deplete more rapidly than vitamin B-12 stores, requiring earlier intervention 2

Vitamin B-12 Replacement

• Vitamin B-12 deficiency results from both reduced gastric acid and loss of intrinsic factor production from parietal cell destruction 2, 3
• Pernicious anemia represents a late-stage manifestation of autoimmune gastritis characterized by vitamin B-12 deficiency and macrocytic anemia 1
• Intramuscular vitamin B-12 supplementation is effective for treating deficiency 4
• The body's substantial hepatic stores of vitamin B-12 can last years, which explains why this deficiency appears later in the disease course compared to iron deficiency 2

Additional Micronutrient Considerations

• Deficiencies of vitamin C, vitamin D, folic acid, and calcium have been increasingly described in autoimmune gastritis patients 5
• Multiple vitamin deficiencies may lead to severe hematological, neurological, and skeletal manifestations 5

Screening for Associated Autoimmune Conditions

• Autoimmune thyroid disease is common in patients with autoimmune gastritis and should be actively screened for 1
• Concomitant autoimmune disorders occur frequently, requiring a systematic approach to detection 1, 3

Surveillance for Gastric Neoplasia

Type 1 Gastric Neuroendocrine Tumors

• All individuals with autoimmune gastritis should be screened for type 1 gastric neuroendocrine tumors with upper endoscopy 1
• Small neuroendocrine tumors should be removed endoscopically 1
• Following removal, surveillance endoscopy should be performed every 1–2 years, depending on the burden of neuroendocrine tumors 1

Gastric Adenocarcinoma Surveillance

• A surveillance endoscopy every 3 years should be considered in individuals with advanced atrophic gastritis, defined based on anatomic extent and histologic grade 1
• The optimal surveillance interval for autoimmune gastritis specifically is unclear and should be based on individualized assessment and shared decision making 1
• In advanced stages, autoimmune gastritis may progress to gastric adenocarcinoma 3, 6

H. pylori Assessment and Eradication

• All individuals with atrophic gastritis should be assessed for H. pylori infection 1
• If H. pylori is positive, treatment should be administered and successful eradication confirmed using non-serological testing modalities 1
• The role of H. pylori in activating or favoring the autoimmune process remains uncertain, but eradication is still recommended 3, 7

Initial Diagnostic Confirmation for New Cases

• Patients with a new diagnosis of pernicious anemia who have not had a recent endoscopy should undergo endoscopy with topographical biopsies to confirm corpus-predominant atrophic gastritis for risk stratification and to rule out prevalent gastric neoplasia, including neuroendocrine tumors 1
• Biopsies from the body and antrum/incisura should be obtained and placed in separately labeled jars 1

Important Clinical Pitfalls

• Iron deficiency presents much earlier than vitamin B-12 deficiency, so waiting for macrocytic anemia before screening for iron deficiency will miss early disease 2
• Hemolytic anemia can rarely occur as a presentation of severe vitamin B-12 deficiency, mimicking thrombotic microangiopathy (pseudothrombotic microangiopathy), which is crucial to recognize to prevent unnecessary plasmapheresis 4
• Antiparietal cell antibodies and intrinsic factor antibodies may be negative in some patients with autoimmune gastritis, so seronegative disease does not exclude the diagnosis 4