PSAT297 Subacute Thyroiditis Following COVID-19 Vaccination

INTRODUCTION: Subacute thyroiditis (SAT) precipitated by COVID-19 infection has been documented in the literature. However, we are now seeing patients develop SAT following the COVID 19 vaccine. Vaccine-related SAT have been reported in the literature, such as in the SARS vaccine. There are now several COVID-19 vaccines being used with benefits on morbidity and mortality. The mechanism of action leading to SAT from the vaccine has not been deciphered, however there are some theories. Here we present a case of COVID-19 vaccine-related SAT. CASE: 42-year-old Caucasian gentleman with no past medical history, presented to the Endocrinology clinic with anterior neck pain around his thyroid area that started 3 days after his 2nd Pfizer COVID-19 vaccine. He described the pain as severe enough to wake him up from sleep. No weight loss, palpitation, heat intolerance or tremors. No prior exposure to stable iodine or radiation treatment. He takes no medications. He denies tobacco or alcohol use. Initial thyroid labs showed a T3 2.8 (2.5 - 4.4 pg/mL), T4 1.4 (0.61 - 1.44 ng/dL), TSH 1.4 (0.45 - 5.33 uIU/mL), TPO antibodies positive, thyroglobulin Ab undetectable, sedimentation rate of 42 (<30 mm/Hr). Ultrasound of the neck showed 1.7-centimeter TIRADS 4 nodules in the left lobe, and 0.9 cm on the right. The patient was noticing a discomfort in the right side of the neck. He was also having swallowing difficulties, low-grade fever, body ache, night sweats and unintentional weight loss. Though he initially presented with thyroid labs that were within the normal reference range, by the time he repeated them one month later, he was hyperthyroid. He was started on prednisone 20 mg and NSAID. At 2 weeks follow-up, his pain and swallowing difficulty have significantly improved. Over time, the patient's thyroid labs normalized and the pain in the neck subsided, repeat neck US 5 months later showed decreased nodule size. Steroids was stopped. DISCUSSION: The common side effects COVID-19 vaccines include pain in the injected site, skin reactions, flu-like symptoms, headache, fatigue and fever. SAT following viral vaccines has been reported previously. The association between SAT and COVID-19 vaccination has come to medical attention more recently due to widespread vaccinations. The mechanism for post-vaccination SAT remains unknown. However, adjuvants contained in vaccines may play a role in producing diverse autoimmune and inflammatory responses and the potential for cross-reactivity between the coronavirus spike protein target produced by the mRNA vaccine and healthy thyroid cells antigens. This case exemplifies the need to know about SAT and COVID 19 vaccine so that clinicians can advise patients to seek medical assistance if experiencing anterior neck pain, extended fever or palpitation so that they are treated properly and in a timely fashion. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.