Gastritis is inflammation of the stomach lining. Autoimmune gastritis (AIG) occurs when the body’s immune system mistakenly attacks its own healthy cells.
Understanding Autoimmune Gastritis
Autoimmune gastritis (AIG) is a chronic condition where the immune system targets parietal cells in the stomach lining. These cells produce hydrochloric acid for digestion and intrinsic factor, essential for vitamin B12 absorption. The immune attack reduces stomach acid (hypochlorhydria or achlorhydria), disrupting digestion and potentially leading to bacterial overgrowth.
It also decreases intrinsic factor, impairing B12 absorption. This malabsorption can cause pernicious anemia, a type of anemia characterized by large, abnormally shaped red blood cells. AIG differs from other common forms of gastritis, such as those caused by H. pylori infection or NSAID use.
Primary Autoimmune Conditions Linked to Gastritis
Autoimmune gastritis often co-occurs with other autoimmune conditions, suggesting shared genetic predispositions. A direct link exists with pernicious anemia, as AIG’s destruction of parietal cells directly impairs intrinsic factor production, leading to severe vitamin B12 deficiency.
Autoimmune thyroid diseases, like Hashimoto’s thyroiditis and Graves’ disease, are significantly associated with AIG. Individuals with Hashimoto’s thyroiditis have an increased risk of developing AIG, and many AIG patients also have autoimmune thyroid disease, sometimes called “thyrogastric syndrome.”
Type 1 diabetes, an autoimmune condition targeting insulin-producing cells, also co-occurs with AIG. This suggests susceptibility to multiple organ-specific autoimmune diseases. Vitiligo, where the immune system attacks pigment-producing cells, is also associated with AIG, highlighting the systemic nature of autoimmune responses.
Less common associations include Addison’s disease, affecting the adrenal glands, and celiac disease, an immune reaction to gluten. These connections underscore polyglandular autoimmunity, where a person may develop multiple autoimmune conditions. The presence of one autoimmune condition may prompt screening for others.
Identifying and Diagnosing Autoimmune Gastritis
Recognizing autoimmune gastritis can be challenging due to vague symptoms resembling other digestive issues, such as abdominal pain, indigestion, bloating, and nausea. As the condition progresses, vitamin B12 deficiency can lead to anemia symptoms like fatigue, weakness, and pale skin. Long-term B12 deficiency can also cause neurological symptoms, including tingling, numbness, memory difficulties, and balance problems. These symptoms often develop slowly, making early diagnosis difficult.
Diagnosis typically involves a combination of tests. Blood tests check vitamin B12 levels and detect specific antibodies: anti-parietal cell antibodies (APCA), which target acid-producing cells, and intrinsic factor blocking antibodies (IFBA, more specific for pernicious anemia), which interfere with B12 absorption. An endoscopy with biopsy is the definitive diagnostic method. A doctor uses a thin tube with a camera to visualize the stomach lining and take tissue samples, which are examined for characteristic changes like inflammation, loss of gastric glands, and thinning. Ruling out other causes, such as H. pylori infection, is also important.
Living With Autoimmune Gastritis
Managing autoimmune gastritis primarily addresses its consequences, especially vitamin B12 deficiency. Since the body cannot properly absorb B12, supplementation is typically administered via injections. Initial doses may be frequent, followed by monthly injections for life to maintain B12 levels. Acid-suppressing medications may relieve upper abdominal discomfort but do not treat the underlying autoimmune attack or B12 malabsorption.
Regular medical follow-ups are important due to AIG’s chronic nature and potential for long-term complications. Chronic inflammation can increase the risk of iron deficiency, gastric polyps, and, rarely, gastric cancer. Regular endoscopic surveillance may be recommended to monitor for these changes, especially for individuals with severe atrophy. Maintaining a balanced diet and avoiding gastric irritants may help manage digestive symptoms.