ABSTRACT
A 51-year-old male had a history of well-controlled Graves' disease (GD) under regular follow-up, and thyroid eye disease (TED) with post bilateral orbital decompression. However, after COVID-19 vaccination, recrudescence of GD and moderate-to-severe TED were diagnosed by increased thyroxine levels and decreased thyrotropin levels in serum, and positive results of thyrotropin receptor antibody and thyroid peroxidase antibody. Weekly intravenous methylprednisolone was prescribed. Symptoms gradually improved accompanied with reduction in proptosis: 1.5 mm of the OD and 2.5 mm of the OS. Possible pathophysiological mechanisms discussed included molecular mimicry theory, autoimmune/inflammatory syndrome induced by adjuvants, and certain genetic predisposition of human leukocyte antigen. Physicians should remind patients to seek treatment if the symptoms and signs of TED recur following COVID-19 vaccination.