The Effect of Selenomethionine on Thyroid Autoimmunity in Euthyroid Men With Hashimoto Thyroiditis and Testosterone Deficiency.

Hashimoto (autoimmune) thyroiditis develops much less frequently in men than in women, suggesting that androgens have a protective effect against thyroid autoimmunity. The current study was aimed at investigating whether the effect of selenomethionine on thyroid antibody titers and thyroid function tests in euthyroid men with autoimmune thyroid disease depends on testosterone levels. The study population consisted of 2 age-matched, weight-matched, and thyroid antibody titer-matched groups of euthyroid men with Hashimoto thyroiditis and testosterone deficiency: 18 patients receiving intramuscular testosterone enanthate (100 mg once weekly) and 19 testosterone-naive men. All subjects were than treated with selenomethionine (200 µg daily) for 6 months. Serum titers of thyroid antibodies, thyrotropin, free thyroid hormones, and testosterone as well as calculated parameters of thyroid homeostasis were assessed at the beginning and at the end of the study. At baseline, except for testosterone, there were no differences between the 2 treatment arms in thyroid antibody titers, serum hormone levels, or values of all calculated indices. Although selenomethionine reduced thyroid peroxidase and thyroglobulin antibody titers in both treatment arms, these effects were stronger in testosterone-treated than in testosterone-untreated men. Only in men receiving testosterone, selenomethionine altered the free thyroxine/free triiodothyronine ratio, testosterone levels, and structure parameter interference approach-GT and structure parameter interference approach-GD. Selenomethionine-induced changes in thyroid antibody titers correlated with the effect of treatment on structure parameter interference approach-GT and testosterone. The obtained results suggest that testosterone determines the strength of selenomethionine action in euthyroid men with autoimmune thyroiditis.