COVID19 Associated Painful Subacute Thyroiditis

Objective: Physicians should be aware that thyroiditis is a potential sequela of COVID-19 infection. Discussion: A 49-year-old female without any prior history of thyroid dysfunction presented with clinical and biochemical hyperthyroidism after a diagnosis of COVID-19 illness four months ago. At the time of thyroiditis diagnosis: free T4 was 1.52 ng/dL (normal, 0.76-1.46 ng/dL), TSH <0.005 uIU/mL (normal, 0.358-3.74 uIU/mL), Thyroglobulin antibodies 2 IU/mL (normal, <=1 IU/mL), TPO antibody 1 IU/mL (normal, <9 IU/mL), ESR 5 mm/hr (normal, 0-20 mm/hr). Thyroid US showed no nodules or evidence of autoimmune thyroid disease or abnormal vascular flow. A radioactive iodine uptake test was performed through the primary care office. The test demonstrated symmetric, uniform radiotracer uptake in the right and left lobe. 24-hour uptake was low at 0.1% (normal 15-25%) indicating thyroiditis. Patient features consistent with the diagnosis of subacute thyroiditis include suppressed TSH, diffuse tenderness on thyroid palpation, absent TPO/TG antibodies, and suppressed I-123 RAI uptake (<1%) on 24-hour scan. Conclusion: There is limited data surrounding thyroid disease and COVID-19. It has been suggested that a possible sequela of COVID-19 is thyroiditis. Physicians caring for recovering COVID-19 patients should be aware of possible painful subacute thyroiditis and to check thyroid studies in persons with symptoms of thyrotoxicosis post-COVID-19.