TG and COVID-19: Her TSH was low, her FT3 was high, and she tested negative for anti-peroxidase antibodies (TPOAb), anti-thyroglobulin antibodies (TgAb), and anti-TSH receptor antibodies (TRAb), [131] Following 15 days after a COVID-19 positive oropharyngeal swab with undetectable TSH, and increased FT4 and FT3.