Endocrine Abstracts

Introduction: Subacute thyroiditis (SAT) is an inflammatory disorder of thyroid associated with viral infections. Rarely, cases of SAT have also been described post-vaccination, but there are not many reports related to exposure to the COVID-19 vaccine. Here, we present a case of subacute thyroiditis after receiving the first dose of a SARS-CoV-2 vaccination inactivated COVID-19 vaccine (Sinovac-CoronaVac, developed by Sinovac/China National Pharmaceutical Group).

Case report: A 36 –year - old male presented to our outpatient endocrinology clinic with complaints of anterior neck pain with irradiation to right ear, fever and fatigue. In his past medical history, he had mild Covid-19 infection in October 2020 and did not report any past medical history for thyroid disease or preceding upper respiratory system infection. He has received his first dose of COVID-19 vaccine 5 days previously. On his physical examination his heart rate was 90/min; body temperature was 37.5 C. On palpation, the thyroid gland was painful and enlarged. The nasopharyngeal swab polymerase chain reaction (PCR) test for SARS-CoV-2 done twice was negative. At laboratory investigations, his thyroid function test was compatible with subclinical hyperthyroidism thyroid stimulating hormone - 0.1 IU/ml (normal range: 0.39-4.2 IU/ml); free thyroxine –1.65 ng/ml (normal range 0.8-2.0 ng/dl). Thyroid autoantibody levels were normal: anty-thyroglobulin antibody - 1.2 IU/ml (normal <4 IU/ml), thyroid peroxidase antibody – 3 IU/ml (normal <20 IU/ml) and anti-TSH receptor antibody – 0.1 IU/l (normal range 0-1.5 IU/l). Levels of erythrocyte sedimentation rate (ESR) and C-reactive protein were elevated (ESR -38 mm/h; CRP – 30 mg/l). Thyroid ultrasound revealed unilateral focal hypoechoic areas with decreased blood flow. Based on clinical symptoms and laboratory examinations, the patient’s diagnosis was considered to be subacute thyroiditis. He was advised to rest, and nonsteroidal anti-inflammatory (NSAIDs) drugs were prescribed; however, the symptoms persisted. Metylprednisolone 24 mg was initiated, and his symptoms rapidly improved after medication.

Conclusion: Post-vaccination SAT cases have so far been rarely reported despite mass vaccination programs in all countries. Roughly 58% of the world population has been already fully vaccinated against covid-19, and there are only a handful number of cases of SAT reported. The development of thyroiditis may occur within a few days, as opposed to more days in case of post-viral illness. Clinicians need to be aware that there is a possibility of SAT post-vaccination and must consider this as a differential diagnosis in a patient presenting with anterior neck pain or fever with a recent vaccination history for adequate patient management and cure.