The Association of Subacute Thyroiditis with COVID-19: a Systematic Review.

The multisystem effects of SARS-CoV-2 encompass the thyroid gland as well. Emerging evidence suggests that SARS-CoV-2 can act as a trigger for subacute thyroiditis (SAT). We conducted a systematic literature search using PubMed/Medline and Google Scholar to identify cases of subacute thyroiditis associated with COVID-19 and evaluated patient-level demographics, major clinical features, laboratory findings and outcomes. In the 21 cases that we reviewed, the mean age of patients was 40.0 ± 11.3 years with a greater female preponderance (71.4%). Mean number days between the start of COVID-19 illness and the appearance of SAT symptoms were 25.2 ± 10.1. Five patients were confirmed to have ongoing COVID-19, whereas the infection had resolved in 16 patients before onset of SAT symptoms. Fever and neck pain were the most common presenting complaints (81%). Ninety-four percent of patients reported some type of hyperthyroid symptoms, while the labs in all 21 patients (100%) confirmed this with low TSH and high T3 or T4. Inflammatory markers were elevated in all cases that reported ESR and CRP. All 21 cases (100%) had ultrasound findings suggestive of SAT. Steroids and anti-inflammatory drugs were the mainstay of treatment, and all patients reported resolution of symptoms; however, 5 patients (23.8%) were reported to have a hypothyroid illness on follow-up. Large-scale studies are needed for a better understanding of the underlying pathogenic mechanisms, but current evidence suggests that clinicians need to recognize the possibility of SAT both in ongoing and resolved COVID-19 infection to optimize patient care.