[The thyroid status in the healthy population of the South-Urals region]

The aim of the investigation was to study the parameters of the thyroid and antithyroid status in the healthy population of different age, living under the conditions of mild iodine deficiency and trace element imbalance in the South Urals (Orenburg). The serum levels of total and free triiodothyronine, total and free thyroxin, thyroid-stimulating hormone (TSH), and antithyroid antibodies were determined and the compensation index and the sensitivity index of thyroid cells to TSH were calculated in 458 apparently healthy individuals aged 7-40 years. TSH levels varied from 0.27 to 3.97 IU/l, amounting to 1.41 +/- 0.03 IU/l. The patients with TSH levels of 0.27 to 0.5 IU/l were found to have a lower compensation index and a higher sensitivity index for thyrocytes to TSH, suggesting the hyperproduction of thyroid hormones in response to low TSH stimulation. The decreased sensitivity index in patients with a TSH level of 2.0 to 4.0 IU/l is a borderline condition. These patients may further develop thyroid hyperplasia if iodine deficiency is not corrected and other strumogenic factors are not used. Higher free T3 levels and decreased compensation index were detected in 83% of the apparently healthy individuals with increased antithyroid antibodies to thyroid peroxidase, which is indicative of the thyroid hyperproduction of T3 and the risk factor of autoimmune diseases.