Does celiac disease increase the risk of autoimmune thyroid disease?

Clinical evidence

• Epidemiological association: Comprehensive clinical studies, including large-scale cohort and case-control evaluations, consistently demonstrate a bidirectional association between celiac disease (CD) and autoimmune thyroid disease (AITD), such as Hashimoto's thyroiditis and Graves' disease. In patients diagnosed with celiac disease, the prevalence of thyroid autoimmunity typically ranges from 10% to 30%, which is significantly higher than in healthy control populations.
• Prevalence metrics: Conversely, the prevalence of biopsy-confirmed celiac disease in patients with autoimmune thyroiditis is estimated to be between 5% and 10%. This represents a 3- to 10-fold increase compared to the general population, which exhibits a celiac disease prevalence of approximately 1%.
• Clinical screening guidelines: Due to this robust epidemiological link, several clinical guidelines recommend routine screening for thyroid dysfunction (measuring thyroid-stimulating hormone [TSH] and anti-thyroid peroxidase [TPO] antibodies) in patients diagnosed with celiac disease, as well as considering celiac serology screening in patients with established autoimmune thyroiditis who present with atypical gastrointestinal symptoms or unexplained anemia.

Mechanistic explanations

• Shared genetic susceptibility: The primary driver of the co-occurrence of celiac disease and autoimmune thyroid disease is a shared genetic background. Specifically, both conditions are strongly linked to human leukocyte antigen (HLA) class II alleles. The HLA-DQ2 (primarily DQB1*02) and HLA-DQ8 (DQB1*0302) haplotypes, which are required for gluten antigen presentation in celiac disease, are also highly over-represented in individuals who develop autoimmune thyroiditis.
• Immune dysregulation and gluten-induced autoimmunity: The ingestion of gluten in genetically predisposed individuals triggers a chronic, T-cell-mediated inflammatory response in the small intestine. This persistent immune activation leads to systemic inflammation and a breakdown in immune tolerance. Some hypotheses suggest that tissue transglutaminase (tTG) antibodies, or molecular mimicry between gliadin peptides and thyroid proteins, may facilitate the development of autoantibodies targeting the thyroid gland (such as anti-TPO and anti-thyroglobulin antibodies).

Bottom line

Celiac disease is strongly associated with an increased risk of autoimmune thyroid disease, driven by shared HLA-DQ2/DQ8 genetic susceptibility and systemic immune dysregulation. Individuals with either condition should be monitored for signs and symptoms of the other to ensure early detection and management.