Brief Overview: Per UpToDate, “The term metaplastic (chronic) atrophic gastritis, also referred to as gastric atrophy, is used to describe a form of chronic gastritis that, in addition to inflammation, is associated with mucosal thinning, loss of specialized cells in gastric glands, and changes in epithelial cell types (ie, metaplasia).” Autoimmune Metaplastic Atrophic Gastritis (AMAG) is a chronic inflammatory condition in which the body’s immune system attacks the stomach lining, leading to gradual destruction of gastric glands. This causes a lack of stomach acid and intrinsic factor, potentially leading to vitamin B12 deficiency, iron deficiency anemia, and an increased risk of gastric cancer.
Prevalence: According to UpToDate, the prevalence of AMAG is 2%.
Etiology: AMAG is an autoimmune condition that occurs when antibodies attack healthy stomach cells, including intrinsic factor.
Risk Factors:
- Female
- Increasing age
- pylori ? (this is questionable/controversial)
- Family history
Commonly Associated Conditions:
- Autoimmune thyroid disease
- Type 1 diabetes
- Pernicious anemia
- Iron deficiency anemia
Common Medications:
- There is no specific treatment for AMAG
- Vitamin B12, iron replacement as needed
Common Labs, Imaging, and Tests:
- Endoscopy and biopsy
- Lab tests: serologies for anti-intrinsic factor and antiparietal cell antibodies, CBC, fasting gastrin level, serum pepsinogen I, pepsinogen I/II ratio, Vitamin B12 level, iron studies
Common Symptoms:
- Can be asymptomatic
- Upper abdominal discomfort
- Dyspepsia with postprandial distress
- Fatigue
Common Treatments:
- There is no specific treatment for AMAG
- Parenteral replacement of Vitamin B12 if needed
- Treatment of iron deficiency anemia if identified
- Management of any associated conditions
Physical Findings:
- Often normal physical exam
- Decreased vibratory sensation or proprioception (in B12 deficiency)
- Neurologic changes in advanced cases
Potential Complications and Contraindications:
- Pernicious anemia (severe form of Vitamin B12 deficiency) can develop
- Increased risk of gastric neuroendocrine (carcinoid) tumors and adenocarcinomas
- Iron deficiency anemia
- Caution/avoidance of PPIs and H2 blockers
General Health and Lifestyle Guidance:
- Adhere to prescribed B12 and iron therapy as directed by your healthcare provider
- Get routine bloodwork to monitor anemia and vitamin levels as directed by your healthcare provider
- Follow up with gastroenterology for periodic endoscopy as directed
- Discuss with your healthcare provider and/or dietician about eating a balanced diet rich in iron and B12-containing foods (if tolerated) and any other dietary modifications that may be recommended
- Avoid alcohol and smoking
- Discuss screening for other autoimmune conditions if symptoms arise with your healthcare provider
Suggested Questions to Ask Patients:
- Have you experienced fatigue, tingling, or memory problems?
- Do you have a personal or family history of autoimmune diseases?
- Have you been told you have anemia or vitamin B12 deficiency?
- Are you taking acid-suppressing medications?
- Have you had a recent endoscopy or been diagnosed with stomach inflammation?
Suggested Talking Points:
- Work with your healthcare provider and dietician to manage your condition
- You will need regular monitoring of this condition. Make sure to follow up as directed and complete all ordered lab work, tests
- Make sure to report any new, worsening, or persistent symptoms to your healthcare provider
Sources:
- UpToDate
- https://www.merckmanuals.com/professional/gastrointestinal-disorders/gastritis-and-peptic-ulcer-disease/autoimmune-metaplastic-atrophic-gastritis