High prevalence of Antithyroid antibodies in Long COVID fatigue patients

The course and implication of thyroid dysfunction in the context of long COVID fatigue has been reported but is still unclear. Studies point to the role of COVID as a trigger of autoimmunity and its possible association with fatigue. The aim of the present study was to assess the post COVID-19 effects on antithyroid antibodies tests in patients with long COVID fatigue, without previous history of thyroid disease. We conducted a multicenter observational prospective cohort study in three Portuguese hospitals in adults with COVID acute disease diagnosis from Nov2020 to Nov2022, complaining of fatigue 6 months after. We included 166 patients (median age of 54.2 years; 59% female), where 52.4.% had mild, 13.9% moderate and 33.7% severe acute disease. Thyroid function tests and antithyroid antibodies were performed. In these cohort, antithyroid antibodies changes were found in 10.8% of patients, (median age of 48.1 years; 88.9% females), where 77.8% had mild, 5.6% moderate and 16.7% severe acute disease. The presence of high titers of TRAb was the most common change (72.2%), anti-TPO in 27.8% of patients, followed by the presence of Anti-Tg (16.7%). Women were the most affected group by fatigue and concomitantly with thyroid modifications specially with positivity for TRAb which leads us to believe that there may be a link.