New-Onset Thyroid Eye Disease After COVID-19 Infection in Patient with Graves’ Disease Post-Radioactive Iodine Treatment

Introduction:
Coronavirus disease 2019 (COVID-19) has been associated with dysregulation of the immune system and abnormal thyroid function. The aim of this novel case report is to inform physicians of the possibility that COVID-19 infection may precipitate thyroid eye disease (TED) in patients with Graves’ Disease (GD) even after treatment with radioactive iodine (RAI).

Case Description:
In this report, we describe a patient with GD treated with RAI who developed TED after COVID-19 infection. The patient was initially diagnosed with GD in 2018. A thyroid uptake scan (I-123) was consistent with GD with moderately elevated uptake. She was initially managed with methimazole and atenolol and was eventually treated with RAI (16.32 millicurie I-131) in February 2021. She had post-ablative hypothyroidism managed with levothyroxine. The patient contracted COVID-19 in January 2022. In February 2022, the patient started experiencing eye irritation, dryness, protrusion of eyes, eyelid swelling, and visual disturbances. Thyroid stimulating hormone (TSH) receptor auto-antibodies (7.33 IU/L, normal < /=1.00 IU/L) and thyroid stimulating immunoglobulin (4.30 IU/L, normal < /=1.00 IU/L) were elevated. TSH was normal (2.180 mIU/L, normal 0.270 - 4.200 mIU/L) on levothyroxine 125 mcg daily. She was later diagnosed with TED.

Discussion:
GD is an autoimmune thyroid disorder related to the presence of TSH receptor-stimulating antibodies and is often associated with ocular symptoms. Activation of an autoimmune response during COVID-19 infection, may induce onset or relapse of GD.  A study using the national health insurance service database in South Korea noted an increase in the incidence of subacute thyroiditis in 2020 in association with the COVID-19 pandemic.

TED is usually seen in patients with GD. Radioactive iodine is widely used in the treatment of GD and has been associated with development or worsening of TED. There are published cases of TED occurring in patients with GD after receiving COVID-19 vaccine. It is thought that the inflammatory syndrome induced by the adjuvants could induce molecular mimicry, which could trigger TED. In most cases this adverse effect was transient, lasting a few months after treatment. There have been case reports of TED occurring after 3 to 21 days of COVID-19 vaccination in patients with controlled GD. Symptoms improved in 4-8 months. Development of TED in patients with GD who have been treated with RAI typically occurs soon after RAI therapy. For TED to occur in a GD patient 11 months after receiving RAI therapy is unusual. COVID-19 infection appears to have been the trigger for this patient's eye disease. This is highly unusual and has not been published to our knowledge.