The aim of the study was to determine the number of cases of newly diagnosed hypothyroidism, as well as to establish a link between the development of decompensated hypothyroidism and a previous COVID-19 infection among patients followed up by an endocrinologist over the past three years. As part of the study, the authors analyzed data from outpatient records of 317 patients diagnosed with “autoimmune thyroiditis, manifest hypothyroidism”, who were under the supervision of an endocrinologist at Belgorod State University Polyclinic from January 2021 to December 2023. The assessment of endocrine dysfunction of the thyroid gland was based on a comprehensive clinical, laboratory and instrumental diagnosis of patients. The obtained results were statistically processed using the IBM SPSS Statistic 26 program. The study revealed a significant increase in the number of cases of newly diagnosed hypothyroidism in 2023 compared to 2021, 26.7 % and 10.7 %, respectively, as well as in the number of patients with decompensated hypothyroidism among those previously observed by an endocrinologist for this disease. A more severe course of hypothyroidism in the outcome of autoimmune thyroiditis was established among patients who had suffered from COVID-19 infection. A history of new coronavirus infection is an undeniable risk factor for the development of thyroid pathology. Examination of thyroid function is mandatory in patients who have suffered a new coronavirus infection, including among patients with hypothyroidism with autoimmune thyroiditis who have been followed up by an endocrinologist for a long time.