TPO and COVID-19: A similar study found that the serum concentrations of TSH and total T3 were considerably lower in patients with COVID-19 than in a control group.5 Another study of hospitalized COVID-19 patients conducted in Hong Kong showed that the majority of those with abnormal thyroid function (13.1% of the group) had low TSH concentrations, but only one of 191 participants (0.5%) had a high TSH concentration and a high TPO antibody titre.6 Abnormal thyroid function was common in patients with COVID-19, particularly hyperthyroidism in another study.7,15