Endocrine Abstracts

Selenium (Se) supplementation has been adopted as treatment for patients with elevated autoantibodies or in patients with mild Graves’ orbitopathy. However, serum Se concentrations or other markers of Se status are usually not determined during treatment. The aim of our study was to measure serum Se concentrations at regular intervals during treatment and to register any side effects.

Twenty patients with mild orbitopathy and twenty patients with active autoimmune thyroiditis participated in the study. The following clinical parameters were determined: TSH, fT4, fT3, TSH receptor antibodies, anti-TPO and thyroglobulin antibody levels. In case of orbitopathy, the status of the orbit was registered at the beginning of the study and during treatment. The patients received 100 or 200 μg organic or inorganic Se daily. Se levels were measured before supplementation was started and at regular intervals during treatment. Altogether 168 serum Se concentrations were determined by hydride generation atomic absorption spectrometry.

In case of autoimmune thyroiditis, autoantibody levels decreased. Generally, thyroglobulin antibody levels decreased faster with concurrent Se supplementation than anti-TPO levels. In patients with orbitopathy, ATA and clinical activity scores improved in the majority of study participants and worsened only in patients whose serum Se levels did not increase. Mean Se concentrations were 83.2±13.4 ng/ml (range: 59.1–92.0 ng/ml) before supplementation started and 136.7±22.0 ng/ml (range: 118.18–220.84 ng/ml) up to two years later (P<0.001). The effect of Se supplementation varied greatly between patients. Se levels surpassed the reference range much faster than previously reported. There were no side effects registered.

These are the first Hungarian data representing the effect of Se supplementation in patients with autoimmune thyroiditis and mild orbitopathy. Se concentrations increased significantly regardless whether organic or inorganic Se was administered. In summary, serum Se levels of patients receiving Se supplementation should be controlled regularly, at least every six months.