Serum Zonulin Levels in Patients with Hashimoto's Thyroiditis

Objective: Hashimoto's thyroiditis, also known as chronic lymphocytic thyroiditis, is the most common autoimmune thyroid disease in children and adolescents. The exact mechanism that triggers autoimmunity in Hashimoto's thyroiditis is not fully known. Many pathologies, including the disruption of the intestinal epithelial barrier that causes the production of an inappropriate immune response by the interaction of submucosal immune cells with the antigens, have been accused. Zonulin is a protein that modulates the permeability of tight junctions between intestinal mucosal cells. Abnormal up-regulation of Zonulin causes increased intestinal permeability and is central to the development of autoimmune diseases.Methods: A total of 53 adult patients with newly diagnosed Hashimoto's thyroiditis, 70 adult patients with previously diagnosed Hashimoto's thyroiditis, receiving thyroid hormone replacement therapy and 62 healthy controls were enrolled in the study. Patients with other autoimmune or systemic disorders were excluded. Hemogram parameters, biochemical variables and serum zonulin levels of the participants were examined.Results: There was no significant zonulin elevation in the newly diagnosed Hashimoto's thyroiditis patient group or in the previously diagnosed Hashimoto's thyroiditis patient group currently receiving replacement therapy compared to the control group. Zonulin levels, which have an important place in the intestinal permeability modulation, can be affected by environmental factors, so they should be carefully evaluated. A statistically significant correlation was observed between zonulin levels and anti-thyroid peroxidase (anti-TPO) antibody levels in patient groups included in our study. There is also a significant correlation between zonulin levels and age, body mass index and cholesterol values.Conclusion: A correlation between anti-TPO levels, an indicator of autoimmunity, and serum zonulin levels suggests that this molecule plays a role in the pathogenesis of Hashimoto's thyroiditis. The results of this study should be supported by larger-scale studies with longer follow-up periods.