Selenium and Thyroid Health in NZ European Women

The primary aim of the study was to determine differences in the hormonal status (TSH, T3, and T4) between healthy participants and participants with Hashimoto’s thyroiditis. The secondary aim of the study was to assess plasma selenium nutritional status and its relationships with the serum levels of thyroid hormones in both of the groups. This study is a pilot and a cross-sectional. Study participants were assigned into two groups, the control group with healthy participants (n=13) and a group of women with Hashimoto’s thyroiditis (n=8). Any change in the participants’ daily routine was not required. For the measurement of plasma selenium, thyroid stimulating hormone, tetra iodothyronine, and triiodothyronine, creatinine, and glomerular filtration rate, participants’ non-fasting blood samples were taken. Two women with subclinical hypothyroidism were excluded from the statistical data analyses. Women with Hashimoto’s thyroiditis were older, had higher tetra iodothyronine level, low triiodothyronine/tetra iodothyronine ratio, higher plasma selenium levels, and similar triiodothyronine plasma levels to women in the control group. Significant relationships between triiodothyronine and selenium, triiodothyronine were identified in the group of women with Hashimoto’s thyroiditis. There was a moderate selenium deficiency in both of the groups that affected more women with hypothyroidism. Compromised peripheral deiodination in women with hypothyroidism required increased L-thyroxine dosing, which in turn increased the level of tetra iodothyronine, and decreased pituitary thyroid stimulating hormone, in order to achieve the desired level of the triiodothyronine. In order to increase plasma selenium level, recent research has suggested that selenium supplementation with selenomethionine or selenium selenite, might also slow down the process of thyroid destruction by thyroid autoantibodies in Hashimoto’s thyroiditis. In the past, the process of selenium supplementation had variable success rates. Therefore, further research is warranted. Abbreviations: TSH: Thyroid stimulating hormone; T3: Triiodothyronine; T4: Tetraiodothyronine; SeMet: Selenomethionine; SeCys: selenocysteine