THYROID SCREENING AND RELIABILITY OF RADIATION THYROID DOSES FOR THE BELARUSIAN IN UTERO COHORT

Abstract

Objective. To describe the status and results of thyroid disease screening and assessment of reliability of radiation thyroid doses in the Belarusian in utero cohort of 2,965 individuals exposed to Chernobyl (Chornobyl) fallout. Materials and methods. Thyroid screening examinations are currently underway including thyroid palpation by an endocrinologist, ultrasonographic examination by an ultrasonographer and analysis of blood samples for diagnosis of hypo-and hyperthyroidism, autoimmune thyroiditis, thyroid function tests (thyroid-stimulating hormone [TSH], thyroxine [T4], thyroid peroxidase antibody [anti-TPO], and thyroglobulin antibodies [anti-TG]). Reliability of (i) information from 780 pairs of questionnaires obtained during the first and second interviews of the mothers and (ii) thyroid doses, which were calculated for the cohort members using this information, is evaluated. Results. As of 15 August 2021, 1,267 in utero exposed study subjects had been screened. A single thyroid nodule was diagnosed in 167 persons (13.2 % of the total) and multiple thyroid nodules in 101 persons (8.0 %): 189 (14.9 %) persons had nodules detected for the first time at the screening while 79 (6.2 %) persons had nodules detected previously (pre-screening nodules). Fifty-nine out of 268 subjects (22.0 %) with a suspicious thyroid nodule were referred to fine needle aspiration biopsy, and among them 33 (55.9 %) were biopsied. Reasonable agreement was observed for model-based doses calculated for the Belarusian in utero cohort members using data from the two interviews (Spearman’s rank-correlation coefficient rs = 0.74, p < 0.001), while measurement-based doses yielded almost perfect agreement (rs = 0.99, p < 0.001). Conclusions. During the thyroid screening, at least one thyroid nodule was identified in 268 of 1,267 (21.2 %) in utero exposed cohort members. Seven thyroid cancer cases were identified in the cohort, including 5 pre-screening cases and 2 cases detected during the screening. Ongoing research on this unique cohort will provide important information on adverse health effects following prenatal and postnatal exposure to radioiodine and radiocesium isotopes, for which available epidemiological data are scant.