Plasma selenium status in newly diagnosed Graves’ disease and Hashimoto’s thyroiditis patients: case-control study

Selenium status is an important marker of general population health. It has been hypothesized that nutritional selenium deficiency may trigger the development of thyroid autoimmunity. Furthermore, relatively low selenium levels have been found in patients with autoimmune thyroid diseases (AITD). Very little information is currently available on the selenium status in AITD in Latvia. We aimed to assess selenium status in patients with newly diagnosed, treatment-naïve Graves’ disease (GD) or Hashimoto’s thyroiditis (HT). Selenium status was assessed by measuring plasma selenium and selenoprotein P (SEPP) levels, and glutathione peroxidase (GPx) activity in the blood of 12 GD and 46 HT patients compared to 39 healthy subjects. GPx activity was determined by the methods of Paglia and Valentin. Plasma selenium level was determined using the Alfthan fluorimetric method, whereas SEPP levels were measured by ELISA. Results shown as median (interquartile range). Serum selenium level was 83.98 (68.22-111.59) µg/L in control group, 90.17 (66.03-119.94) µg/L in HT group, and 70.70 (58.86-104.40) µg/L in GD group (p=0.253). GPx level was 12962 (9350-14792) U/L in control group, 12827 (10191-15006) U/L in HT group, and 10571 (7526-13194) U/L in GD group (p=0.203). SEPP level was 6.41 (4.37-7.85) mg/L in control group, 6.92 (4.94-9.50) mg/L in HT group, and 5.79 (4.52-7.71) mg/L in GD group (p=0.750). No significant differences in selenium, SEPP or GPx levels were found among the studied groups. In GD patients, anti-TSHR antibody levels correlated significantly with GPx (rho=-0.718, p=0.013). In addition, we found that Se positively correlated with SEPP in HT patients (rho=0.392, p=0.007). The selenium status of Latvian patients with new-onset GD or HT was at a suboptimal level – only 23.91% of the HT patients and 8.33% of the GD patients had optimal (>120μg/L) plasma selenium levels.This study was supported by the Latvian Council of Science (Grant No: lzp-2018/2-0059).