Prevalence of thyroid autoimmunity in first-degree relatives of patients with celiac disease.

Aim: Patients with celiac disease (CeD) are prone to develop other autoimmune diseases such as autoimmune thyroid disease and type 1 diabetes. While 7.5% of first-degree relatives (FDRs) of patients with CeD develop CeD, it is not clear whether FDRs of patients with CeD are at higher risk of developing autoimmune thyroid disease.

Methods: In this prospective case-control study, we recruited 194 FDRs (males 53.1%) of 91 patients with CeD and 140 age-matched healthy controls (males 76.4%). They were screened for CeD using anti-tissue transglutaminase antibodies (anti-tTG Ab) and thyroid disease using a symptom questionnaire, anti-thyroid peroxidase antibodies (anti-TPO) and serum thyroid-stimulating hormone (TSH). Subjects having positive anti-TPO but a normal TSH were classified as having thyroid autoimmunity and those with elevated TSH with or without positive anti-TPO Ab were classified as having autoimmune thyroid dysfunction.

Results: The prevalence of thyroid autoimmunity and autoimmune thyroid dysfunction in FDRs was significantly higher than that in healthy controls (17.5% vs. 5.0%, p < 0.01; 11.8% vs. 3.5%, p < 0.01), respectively. A significantly higher number of FDRs had a positive anti-tTG Ab in comparison with controls (13.9% vs. 2.2%, p < 0.001). Amongst FDRs having thyroid autoimmunity, 44.1%, 47.0% and 8.8% were siblings, parents and children of patients with CeD, respectively. Familial clustering was seen only in 1 family.

Conclusion: FDRs of patients with CeD have 3-fold higher risk of developing autoimmune thyroid disorders and associated thyroid dysfunction. Therefore, it is advisable for early screening of FDRs for CeD and associated thyroid autoimmune through screening measures.