Mohamed Reda Halawa
Endocrinolgy & Metabolism, Faculty of Medicine, Ain Shams University
Iman Zaky Ahmed
Endocrinolgy & Metabolism, Faculty of Medicine, Ain Shams University
Yara Mohamed Eid
Endocrinolgy & Metabolism, Faculty of Medicine, Ain Shams University
Zeinab Ahmed Youssef Ashour
Professor of Allergy & Clinical Immunology, Faculty of Medicine, Ain Shams University
Maha Ahmed Anwar
Clinical Pathology Departments, Faculty of Medicine, Ain Shams University
Mina Michael Nesim
Endocrinolgy & Metabolism, Faculty of Medicine, Ain Shams University
Caroline Adel Girgis Bishay
Endocrinolgy & Metabolism, Faculty of Medicine, Ain Shams University
ABSTRACT
Background: Hashimoto’s thyroiditis (HT) is the most prevalent autoimmune thyroid disorder globally. Emerging evidence suggests a role of increased intestinal permeability—commonly referred to as "leaky gut"—in the pathogenesis of autoimmune diseases. Zonulin, a regulator of intestinal tight junctions, has been proposed as a marker of intestinal permeability. Its relationship to HT and gut microbiota, especially Lactobacillus acidophilus, remains understudied. Objective: To evaluate the association between serum zonulin levels and the presence of Lactobacillus acidophilus in stool with the occurrence and severity of HT. Methods: This cross-sectional study included 80 Egyptian adults (20–60 years), comprising 60 patients with HT and 20 controls. HT patients were subcategorized into euthyroid, subclinical, and overt hypothyroid groups. Serum zonulin, thyroid function tests, thyroid peroxidase antibodies (TPO Ab), and stool culture for Lactobacillus acidophilus were assessed. Results: Zonulin levels and Lactobacillus acidophilus prevalence were significantly elevated in HT patients, especially in the hypothyroid subgroup. Zonulin showed positive correlation with TPO Ab and TSH, and a negative correlation with FT4. A zonulin level >17 ng/ml predicted TPO Ab positivity with 71.67% sensitivity and 100% specificity (AUC=90.2). Patients with positive Lactobacillus acidophilus cultures exhibited higher zonulin, TPO Ab, and TSH levels compared to those with negative cultures. Conclusions: Elevated serum zonulin and increased intestinal colonization by Lactobacillus acidophilus are significantly associated with HT, suggesting a potential link between intestinal permeability and thyroid autoimmunity. These findings support a role for gut-thyroid axis dysregulation in HT pathogenesis.
Keywords: Hashimoto’s Thyroiditis; Zonulin; Leaky Gut Syndrome; Lactobacillus Acidophilus; Thyroid Autoimmunity; Intestinal Permeability.
