Endocrine Abstracts

We report the development of de novo thyroid eye disease (TED) following COVID-19 vaccination, that occurred several years after administration of radioiodine (RAI) therapy for Grave’s disease, rendering the patient hypothyroid and requiring levothyroxine replacement therapy. A 52-year-old lady, who had previously been treated with RAI for an overactive thyroid gland, presented 5 years later with symptoms of dryness and protrusion of her left eye, that was initially noticed within a few weeks after receiving the first dose of AstraZeneca COVID mRNA vaccine. She was a smoker with a 40-pack year history. Clinical examination revealed exophthalmos, lid lag, and chemosis in the left eye. Of note, her euthyroid status was maintained clinically and biochemically on a consistently stable dose of Levothyroxine 75/100 micrograms on alternate days throughout the 5 years following radioactive iodine therapy and even at the time of development of TED, with no significant alterations to the dosage being required in between or subsequently. Thyroid receptor antibodies (TRAb) levels significantly worsened from 2.5IU/l (0.1- 0.9) before radioactive iodine therapy to 45IU/l (0.1-0.9) at the time of development of TED and continued to rise thereafter as well. Several reports suggest the role of adjuvants in COVID vaccines as the possible trigger for the autoimmune inflammatory response causing an immune dysregulation, much like the virus per se. Molecular mimicry and genetic predisposition of human leukocyte antigen are other suggested pathophysiological mechanisms, including the possibility of immune reactivation of residual thyroid gland remnants by TRAb. This case highlights the need for clinicians to be vigilant of such clinical situations and to closely monitor patients with prior thyroid disease receiving COVID vaccinations. It is imperative to collaborate with Ophthalmologists in the joint thyroid eye clinic as it becomes even more pertinent in these well recognised circumstances but less commonly perceived scenarios.