Influence of excessive iodine intake on the thyroid function and spectrum of thyroid abnormalities in population of Turinsk, Sverdlovsk Region, of Russia

Abstract

Background. Previous surveys showed chronic iodine excess - median urinary iodine concentration (UIC) over 500 mcg/l supposedly due to water contamination in population of Turinsk, a town in Sverdlovsk Region of Russia. Aim. Conduct an assessment of the effects of chronic iodine excess on thyroid function and spectrum of thyroid abnormalities in schoolchildren and adults. Materials and methods. Assessment was conducted in 100 schoolchildren and 100 adults residing in Turinsk and 97 schoolchildren and 100 adults in the control site (city of Pervouralsk) with optimal UIC. Assessment included thyroid ultrasonogrpahy, urinary iodine and dry spot TSH in schoolchildren and TSH and TPO-ab in adults. Iodine was also measured in random water samples from 10 households in Turinsk. Results. Median UIC in schoolchildren in Turinsk (719 mcg/l) was significantly higher (129 mcg/l) than in Pervouralsk resulting in higher prevalence of thyroid enlargement and TSH level. In adults TSH level as well as prevalence of sub-clinical hypothyroidism and autoimmune thyroiditis were higher in residents of Turinsk compared to control group from Pervouralsk. Conclusions. Iodine excess alters thyroid function in schoolchildren and adults increasing prevalence of thyroid enlargement in children and autoimmune thyroidis in adults.

Keywords

• excessive iodine intake
• subclinical hypothyroidism
• autoimmune thyroiditis
• diffuse goiter
• tsh
• urinary iodine
• turinsk