TPO and hyperthyroidism: In a series of the Ukrainian–American Cohort Study of Thyroid Cancer and Other Thyroid Diseases Following the Chornobyl Accident [carried out 12–14 years after the accident (1998–2000), in which the mean thyroid 131I dose was 0.79 Gy, range, 0–40.7 Gy [33], a significant correlation between thyroid 131I dose and the prevalence of hypothyroidism (6.1%, 719/11 853) and thyroid autoimmunity (i.e. positive anti-TPO antibodies) (11.9%, 1456/12 240), but not the prevalence of hyperthyroidism (0.6%, 76/11 853) or autoimmune thyroiditis (1.6%, 196/12 240), was observed [34–36].