Analysis of prevalence of thyroid disorders in children of Kaluga oblast exposed to iodine-131 in prenatal and postnatal periods until the age of 7 years
The article analyzes the prevalence of thyroid disorders developed within 12-year period of follow-up of children exposed to iodine-131 in prenatal and postnatal periods until the age of 7 years. All of the children and pregnant women resided in iodine-deficient south-west rayons of Kaluga oblast during the first three months after the Chernobyl accident. Thyroid disorders were found in 55 of 420 children exposed to radioiodine in utero, 175 of 692 exposed newborns and breastfed children, 343 of 1058 children exposed at the age between 1-3 years and 758 of 1853 children exposed at the age between 3 and 7 years. In the same control age groups thyroid dysfunction was found in 8 of 150, 19 of 220, 44 of 314, 85 of 846 of unexposed children respectively. The nontoxic diffuse goiter of the first and second classes was the common disease among the first diagnosed thyroid disorders in exposed and unexposed children. Nodular goiter, autoimmune thyroiditis and thyroid hypoplasia were found as well. No cases of autoimmune thyroiditis were found in children exposed to iodine-131 in utero, at the same time, in exposed newborns and breastfed children the percentage of autoimmune thyroiditis was the highest among other detected thyroid abnormalities detected in this age group and exceeds the percentage of the disease cases in the older children (3.43% and 0.91%, p<0.05 respectively). In exposed in prenatal the percentage of thyroid hypoplasia was higher than in children exposed in postnatal period - 5.45% and 0.55%, p<0.05 respectively. The conclusion of the study is that exposure to radioiodine is one of the causes of thyroid abnormalities developed in children.