The impact of the COVID-19 pandemic on chronic lymphocytic thyroiditis: A single-center retrospective analysis

COVID-19 pandemic profoundly impacted global health, yet its effects on autoimmune thyroid diseases, particularly chronic lymphocytic thyroiditis (CLT), remain unclear. We aimed to evaluate how clinical, laboratory, and radiological features of CLT changed across distinct phases of the pandemic.

In this single-institutional retrospective study, we included 7717 patients who underwent thyroidectomy with histologically confirmed CLT from January 2015 to August 2024, excluding those with concurrent autoimmune diseases or incomplete clinical data. Patients' data were stratified into pre-pandemic (before January 2020), pandemic (January 2020-October 2021), and post-pandemic (after October 2021) periods. Demographics, thyroid function tests, autoantibody titers (thyroid peroxidase antibody [TPOAb] and thyroglobulin antibody [TgAb]), ultrasonographic features, and thyroid hormone dosages were compared. Predictors for disease-related outcomes were identified using monthly aggregated interrupted time series analyses.

Age distribution was consistent among groups, but the proportion of female sex significantly decreased (90.0 % pre-pandemic, 87.0 % post-pandemic; p < 0.001) and body mass index increased (23.3 ± 3.5 kg/m² pre-pandemic, 23.6 ± 3.3 kg/m² post-pandemic; p < 0.001). TPOAb levels were significantly elevated during the pandemic (145.6 ± 275.6 IU/mL) and post-pandemic periods (172.4 ± 273.4 IU/mL) compared to pre-pandemic levels (103.5 ± 270 IU/mL, p < 0.001). TgAb levels were predominantly elevated during the pandemic period (320.4 ± 548.9 vs. 242.8 ± 585 IU/mL pre-pandemic, p < 0.001). Ultrasound features suggestive of CLT, autoantibody positivity and elevated TSH levels were all significantly associated with an increased prevalence after the pandemic (p < 0.05).

The COVID-19 pandemic significantly influenced CLT characteristics, including altered autoantibody profiles, radiological manifestations, and increased thyroid hormone requirements. Therefore, consideration of pandemic-driven changes during patient management is urged.