Celal Bayar University, Medical Faculty, Department of Internal Medicine, Division of Endocrinology, Manisa, Turkiye, Celal Bayar University, Medical Faculty, Department of Internal Medicine, Division of Immunology, Manisa, Turkiye, Celal Bayar University, Medical Faculty, Department of Clinical Biochemsitry, Manisa, Turkiye
Background. Hashimoto’s thyroiditis is a chronic, organ-specific autoimmune disease. It is the most common cause of primary hypothyroidism during the adolescent period, via autoimmune thyroid tissue destruction, affecting 2% of the population. The pathogenesis of Hashimoto’s thyroiditis involves a complex interaction between predisposing genetic and environmental factors. Objective. In this study, we wanted to investigate the role of cytokines such as IL-2, IL-4, IL-12 and IFN-γ in the pathogenesis of the disease, and the changes to cytokine levels brought about by treatment with L-thyroxine. Methods. Sixty five female patients, aged 18-73 years with Hashimoto’s thyroiditis, referred to the Celal Bayar University Medical Faculty Endocrinology out-patients clinic, were included in this study. After a 10-12 week period of L-thyroxine treatment, all patients were restored to the euthyroid state. At the beginning and end of the treatment period, serum-free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), autoantibodies against thyroid peroxidase (anti-TPO), autoantibodies against thyroglobulin (anti-Tg) levels were measured using a chemiluminecent, immunometric method, and cytokine levels were measured using ELISA. Results. There was a statistically significant decrease in the serum levels of TSH (p < 0.0001) and a concomitant increase in FT4 serum levels (p < 0.0001). Also, during the post-treatment period, serum levels of anti-Tg (p < 0.01) and anti-TPO (p < 0.001) were significantly lower than during the pre-treatment period. A statistically significant decrease was shown for interleukin (IL)-12 serum levels during the post-treatment period (p < 0.001). However, the decrease in interferon (IFN)-γ serum levels was not statistically significant (p = 0.276). On the other hand, no change was demonstrated in serum IL-2 and IL-4 levels (p = 0.953 and p = 0.313, respectively) after treatment with L-thyroxine. Conclusion. Considering that our study involved a 10-12 week period of treatment, the statistically significant decrease in serum IL-12 levels, and the statistically non-significant decrease in IFN-γ levels, might indicate that a T helper type 1 inflammatory process had been halted or slowed down.