Study of antithyroid autoimmunity status in children residing in ecologically unfavorable south-west area of the Kaluga oblast

Time changes of prevalence of raised concentration of antibodies to microsomal antigen of thy-rocytes and to thyroglobulin was studied in 6 450 samples of blood sera taken from patients (3 148 men and 3 302 women) born from 1968 to 1986 who resided in Zhizdrinsky, Ulianovsky and Khvastovichsky raions of the Kaluga oblast in 1986. The thyroid of the subjects was exposed to incorporated iodine-131 in May-July 1986 as a result of the Chernobyl accident. The follow-up covers the period from 1987 over 1998. The results of the assay were compared with those of blood sera taken from 1 190 children (604 boys and 586 girls) born in 1987-1997, their thyroid was not exposed to iodine-131. In people with exposed thyroid the frequency of raised concentration of antithyroid antibodies was found to depend on the age at exposure. The older people were at the time of exposure the frequency of raised titer of antibodies to microsomal antigen decreased. The prevalence of the raised level of antithyroid antibodies depended on sex, it was higher in women than in men. In children with unexposed thyroid no dependence of the raised concentration of antithyroid sntibodies on sex was detected. This fact says that the thyroid in women is more sensitive to radiation than that in men. In both groups the frequency of raised level of antithyroid antibodies was higher in patients with thyroid abnormalities. In exposed patients with autoimmune thyroiditis high titers of antibodies to microsomal antigen were found in 96.08 % of persons, high titers of antibodies to thyroglobulin were found in 43.14 % only. In this group high titers of antibodies to thyroglobulin were detected more frequently (7.65 % against 2.96 %) and high titers of antibodies to microsomal antigen were detected more seldom (3.83 % against 7.25 %) if the level of thyrotropin content in blood was high. In the same group there was a trend of relationship between titer of antibodies to microsomal antigen and individual absorbed thyroid dose from iodine-131 and such tendency was not found for antibodies to thyroiglobulin.