Sufficient selenium status is necessary for good thyroid health.
Zuo et al  have investigated selenium status and the effects of selenium supplementation in patients with autoimmune thyroid disease.
They analyzed the data from 17 journal articles based on studies of 1,911 subjects. Their meta-analysis results showed the following statistically significant associations:
- Serum free triiodothyronine (FT3) levels in patients were reduced after selenium supplementation compared to placebo treatment.
- Serum free thyroxine (FT4) levels and anti-thyroid peroxidase antibody (TPOAb) levels were reduced after selenium supplementation compared to placebo treatment.
- Anti-thyroid peroxidase antibody (TPOAb) levels were decreased after selenium supplementation compared to placebo treatment.
However, the thyroid stimulating hormone (TSH) levels
and the anti-thyroglobulin antibody (TGAb) levels were not significantly different between the selenium treatment group and the control group.
The researchers concluded that selenium-containing drugs were effective in treating patients with autoimmune thyroid disease and greatly reduced
the levels of free triiodothyronine, free thyroxine, and anti-thyroid peroxidase antibody in these patients.