FRI468 The Needle And The Crown, Who Is The Culprit? A Case Of Transient Hyperthyroidism In The Setting Of COVID-19 Infection And Recent Thyroid Biopsy

Disclosure: D. Caesario: None. K.L. Hermayer: None. Introduction: Transient hyperthyroidism (TH) is most commonly associated with thyroiditis, such as subacute thyroiditis (SAT). However, TH has also been reported as a complication of thyroid fine needle aspiration biopsy (FNAB), called post-aspiration thyrotoxicosis (PAT). We report a case of TH in the setting of COVID-19 infection and recent thyroid FNAB. Case Report: A 52-year-old male with history of type 1 DM was evaluated for neck enlargement over the past year. Examination was remarkable for enlarged, nontender thyroid. Thyroid function tests were normal. Thyroid US revealed a 7 cm solid mass with calcifications on the right lobe, with extension to the isthmus. The extension was predominantly solid with cystic components. FNAB of the mass showed benign findings. Around 1 week after FNAB, patient developed cough, sore throat, anorexia, neck pain, and multiple vomiting episodes. He had no dyspnea. He was brought to the ED. He was tachycardic and hypertensive, with an enlarged thyroid that was tender. Labs showed leukocytosis with left shift, glucose 651, anion gap 30, TSH 0.03, and free T4 1.68. He tested positive for COVID-19. He was admitted with DKA and COVID-19 infection. He received no steroids due to not meeting the indications for COVID-19 treatment, and was mainly treated for the DKA. Thyroid antibodies were negative and repeat thyroid US revealed no post-biopsy hemorrhage. Hyperthyroidism was deemed to be secondary to SAT and no active intervention was given for it. Repeat free T4 during hospitalization continued to trend down and was subsequently normalized by the time of discharge and outpatient follow-up. Discussion: SAT is a self-limiting inflammatory disorder of the thyroid that typically presents with fever, myalgia, malaise, thyroid pain and tenderness. The usual course of the disease is hyperthyroidism, then hypothyroidism, followed by resolution. Some cases may persist for months or may reoccur. SAT is usually associated with infection of the upper respiratory tract by one of the several common respiratory viruses, and is diagnosed clinically, supported by lab findings of decreased TSH in the setting of negative thyroid antibodies. At the start of the COVID-19 pandemic, it was initially unknown if SARS-CoV-2 virus could also be associated with SAT. However, more cases of SAT following COVID-19 infection have been reported since then. The patient above has findings consistent with SAT in the setting of COVID-19 infection. However, recent FNAB resulting in PAT can also cause TH in his case. PAT was identified in around 1% of thyroid FNAB patients. The affected patients experienced neck pain. Interestingly, thyrotoxicosis occurred only in patients who had a cystic component in the nodule. This patient with a history of recent FNAB might have PAT as a complication, or even in combination with SAT. Although patient’s condition resolved, hyperthyroidism may reoccur in SAT in the future. Presentation: Friday, June 16, 2023