Is Subacute Thyroiditis a Complication of SARS-CoV-2 Infection?

Subacute thyroiditis (SAT) is an inflammatory condition affecting the thyroid gland, usually triggered by a viral infection or occurring after a viral illness. It is characterized by neck tenderness, along with the typical symptoms of thyrotoxicosis and an elevated erythrocyte sedimentation rate. SAT has been identified as a potential complication associated with SARS-CoV-2 infection. The aim of this study is to present and discuss two cases of subacute thyroiditis that occurred following a viral infection, potentially linked to SARS-CoV-2 infection. We describe the clinical, biochemical, and imaging features of two cases of SAT that manifested six weeks after the onset of COVID-19-associated symptoms. Both cases involved female patients, aged 58 and 39, who developed subacute thyroiditis, characterized by neck pain, fever, and fatigue. These symptoms emerged three weeks after recovering from a viral episode marked by acute coryza, cough, and anosmia. Due to a persistent fever lasting three weeks, one of the patients required hospitalization to rule out other infectious causes of prolonged febrile syndrome. Laboratory analyses revealed elevated inflammatory markers, positive serology for SARS-CoV-2 infection, thyroid function tests showed thyroid over-activity and thyroid ultrasound confirmed the diagnosis of SAT. The patients received corticosteroid treatments and beta-blockers, resulting in the complete resolution of symptoms and normalization of inflammatory markers, within three weeks after the SAT diagnosis. Post-COVID-19 thyroiditis can emerge as a potential complication of SARS-CoV-2 infection. It is crucial for clinicians to be aware of this possibility, highlighting the importance of considering post-COVID-19 thyroiditis in patients presenting with relevant symptoms.