Clinical and Biochemical Predictors of Thyroid Autoantibody Levels in Hashimoto's Thyroiditis.

BACKGROUND: Hashimoto's thyroiditis (HT) is the most common autoimmune thyroid disease and is characterized by the presence of thyroid peroxidase (anti-TPO) and thyroglobulin (anti-Tg) antibodies. However, the clinical and biochemical factors associated with these antibodies remain incompletely understood. OBJECTIVE: To evaluate the associations between anti-TPO and anti-Tg antibody levels and demographic, clinical, biochemical, and lifestyle-related factors in patients with HT. METHODS: This retrospective cross-sectional study included 100 patients with HT. Clinical, biochemical, and laboratory data were retrospectively collected from medical records. Group comparisons were performed using non-parametric tests, correlations were assessed using Spearman's rank analysis, and multivariable linear regression was used to identify independent predictors of log-transformed anti-TPO and anti-Tg levels. RESULTS: Anti-TPO levels differed significantly according to TSH status and were independently associated with higher TSH concentrations, longer disease duration, and lower BMI. Smoking was the only independent predictor of anti-Tg levels. No significant associations were observed between thyroid autoantibody levels and age, sex, vitamin D status, or family history of thyroid disease. CONCLUSION: Anti-TPO and anti-Tg antibodies demonstrated distinct clinical associations in patients with HT. These findings support the complementary clinical value of both thyroid autoantibodies and should be confirmed in larger prospective multicenter studies.