Is atrophic gastritis associated with Hashimoto thyroiditis?

Atrophic Gastritis and Hashimoto's Thyroiditis: A Significant Association

Yes, atrophic gastritis is strongly associated with Hashimoto's thyroiditis, with up to one-third of patients with autoimmune thyroid disease having autoimmune gastritis. 1

Understanding the Association

• Autoimmune gastritis (AIG) has an established association with other autoimmune diseases, especially autoimmune thyroid disease, likely due to shared genetic susceptibility loci 1
• This association has been recognized since the early 1960s and was originally termed "thyrogastric syndrome" 2, 3
• The relationship is now classified as part of polyglandular autoimmune syndrome type IIIb, in which autoimmune thyroiditis represents the pivotal disorder 3

Epidemiological Evidence

• Approximately one-third of patients with autoimmune thyroid disease have autoimmune gastritis 1
• Conversely, about 40% of patients with autoimmune gastritis also present with Hashimoto's thyroiditis 3
• In a recent study of 840 Hashimoto's thyroiditis patients, 21.4% had positive anti-parietal cell antibodies (APCA), which are screening markers for autoimmune gastritis 4

Clinical Implications

• Patients with autoimmune gastritis should be screened for autoimmune thyroid disease due to this strong association 1
• Conversely, patients with Hashimoto's thyroiditis should be evaluated for signs of autoimmune gastritis 2
• This co-occurrence can lead to:
  • Micronutrient deficiencies, particularly iron and vitamin B12 1
  • Potential malabsorption of levothyroxine in patients treated for hypothyroidism 3
  • Increased risk for gastric malignancies 2, 4

Diagnostic Considerations

• In patients with Hashimoto's thyroiditis who have unexplained iron or vitamin B12 deficiency, atrophic gastritis should be considered 1
• APCA-positive Hashimoto's patients are more likely to have:
  • Higher age (54.1 ± 13.5 versus 49.0 ± 14.6 years in APCA-negative patients) 4
  • Higher frequency of positive thyroid peroxidase antibodies (93.3% versus 83.9%) 4
  • Higher frequency of other organ-specific autoimmune diseases (14.4% versus 8%) 4
  • Greater risk of gastric neoplasms 4

Management Recommendations

• Patients with autoimmune gastritis should undergo screening for autoimmune thyroid disease 1
• Evaluation for iron and vitamin B12 deficiencies should be performed in patients with atrophic gastritis, especially if corpus-predominant 1
• Consider endoscopic evaluation in patients with unexplained iron or vitamin B12 deficiency to rule out atrophic gastritis 1
• Maintain a low threshold to evaluate for other associated autoimmune diseases, including type 1 diabetes mellitus and Addison's disease, if clinically indicated 1

Potential Complications to Monitor

• Pernicious anemia (a late complication of autoimmune gastritis) 5, 6
• Gastric neuroendocrine tumors (more common in patients with autoimmune gastritis) 1
• Gastric adenocarcinoma (patients with severe atrophic gastritis have increased risk) 1
• Malabsorption of medications, particularly levothyroxine 3

The bidirectional relationship between these conditions highlights the importance of considering one when the other is diagnosed, as early detection can improve clinical outcomes and prevent complications related to untreated disease.