Plasma Selenium Levels in First Trimester Pregnant Women with Hyperthyroidism and the Relationship with Thyroid Hormone Status.

The thyroid gland has the highest selenium (Se) concentration per unit weight among all tissues. The aims of the present study were to evaluate the Se levels in the plasma of hyperthyroidic pregnant women and to investigate the association between maternal plasma Se concentrations and thyroid hormone levels. The study population consisted of 107 pregnant women, 70 healthy pregnant women (group 1) and 37 pregnant women with hyperthyroidism (group 2). The plasma free triiodothyronine (fT3) and free thyroxine (fT4) levels were significantly higher, and the plasma thyroid-stimulating hormone (TSH) and Se levels were significantly lower in group 2 than in group 1 (p < 0.05). A correlation analysis showed a positive correlation between Se and fT4 in group 1 and with TSH in group 2 (p < 0.05). Decreased maternal serum antioxidant trace element Se in hyperthyroidic pregnant women compared with normal pregnant women supported the hypothesis that hyperthyroidism was associated with decreased antioxidant response.