Case of COVID-19 Related Thyroiditis

ABSTRACT

Introduction: The severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) is a novel enveloped RNA beta-coronavirus responsible for the Coronavirus disease-19 (COVID-19) ranging from asymptomatic cases to severe respiratory involvement. The SARS-CoV-2 pandemic has spread rapidly worldwide. Few cases and case series have been published reporting COVID-19 related subacute thyroiditis. We report a case of COVID-19 related thyroiditis. Case Description 73-year-old female presented to the hospital with complaint of shortness of breath, fever and weakness. She was diagnosed with COVID-19 pneumonia and treated with dexamethasone and convalescent plasma. Patient was discharged home after 10 days. Two days after discharge, she presented with complaint of generalized weakness. She was noted to have thyrotoxicosis. Patient was not taking lithium or amiodarone and she did not receive iodinated contrast. She had no sign or symptoms of thyrotoxicosis. She denied neck pain or difficulty swallowing. On laboratory evaluation, SARS Coronavirus 2 RNA was positive. RSV, Influenza A and Influenza B by PCR were negative. TSH was low at 0.182 uIU/mL (0.450-5.330 uIU/mL), free T4 elevated at 3.00 ng/dL (0.58-1.64 ng/dL), free T3 elevated at 5.24 pg/mL (2.20-4.10 pg/mL). Her TSH 3 weeks ago was normal at 0.723 uIU/mL. Thyroid stimulating immunoglobulin negative < 0.10 (< =0.54 IU/L). Thyroid ultrasound showed normal sized gland, few sub centimeter nodules bilaterally. NM thyroid uptake and scan showed low uptake and no focal hot or cold nodule. Her workup was consistent with thyroiditis. Correlating with the diagnosis of COVID-19, this could be most likely COVID-19 related thyroiditis. Repeat labs in a week showed normal TSH 1.138 uIU/mL, normal free T4 1.28 ng/dL and low free T3 1.93 pg/mL. The patient likely had thyroiditis during early course of COVID-19 infection and was caught during the late phase and hence, improvement of thyroid function within a week of biochemical diagnosis. Discussion: Subacute thyroiditis is a self-limited inflammatory disorder, characterized by neck pain, general symptoms and thyroid dysfunction. It has been linked to viral infection like mumps virus, coxsackievirus, adenovirus, Epstein-Barr virus, rubella and cytomegalovirus. In our patient, SARS-CoV-2 was the likely cause of thyroiditis. A single center retrospective study done in 287 patients hospitalized with COVID-19 in Milan, Italy reported 20% of patients with thyrotoxicosis, 5% with hypothyroidism and 74% with normal thyroid function test. We report this case to alert clinicians that thyroiditis and resultant thyrotoxicosis should always be considered as a differential diagnosis in patients with COVID-19.