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-gamma 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)-gamma 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-gamma levels, might indicate that a T helper type 1 inflammatory process had been halted or slowed down.