Thyroid sequelae of COVID-19: a systematic review of reviews

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has the potential to cause multi-organ effects including endocrine disorders. The impact of COVID-19 on the thyroid gland has been described but several aspects have to be clarified. The systematic review was conceived to achieve more solid information about: 1) which thyroid disease or dysfunction should be expected in COVID-19 patients; 2) whether thyroid patients have a higher risk of SARS-CoV-2 infection; 3) whether the management has to be adapted in thyroid patient when infected. The literature was searched by two authors independently. A 5-step search strategy was a priori adopted. Only reviews focused on the relationship between thyroid and COVID-19 were included. The last search was performed on February 21^st 2021. Two-hundred-forty-seven records was initially found and nine reviews were finally included. The reviews identified several potential thyroid consequences in COVID-19 patients, such as thyrotoxicosis, low-T3 syndrome and subacute thyroiditis, while no relevant data were found regarding the potential impact of COVID-19 on the management of patients on thyroid treatment. The present systematic review of reviews found that: 1) patients diagnosed with COVID-19 can develop thyroid dysfunction, frequently non-thyroidal illness syndrome when hospitalized in intensive care unit, 2) having a thyroid disease does not increase the risk for SARS-CoV-2 infection, 3) thyroid patients do not need a COVID-19-adapted follow-up. Anyway, several factors, such as critical illness and medications, could affect thyroid laboratory tests.