Abstract
Thyroid gland can be affected by the COVID-19 infection. The pattern of thyroid
function abnormality reported in COVID-19 is variable; in addition, some drugs
used in COVID-19 patients like glucocorticoids and heparin can affect the
thyroid function tests (TFT). We conducted an observational, cross-sectional
study of thyroid function abnormalities with thyroid autoimmune profile in
COVID-19 patients with varying severity from November 2020 to June 2021. Serum
FT4, FT3, TSH, anti-TPO, and anti-Tg antibodies were measured before the
initiation of treatment with steroids and anti-coagulants. A total of 271
COVID-19 patients were included in the study, of which 27 were asymptomatic and
remaining 158, 39, and 47 were classified to mild, moderate and severe
categories, respectively, according to MoHFW, India criteria. Their mean age was
49±17 years and 64.9% were males. Abnormal TFT was present in
37.2% (101/271) patients. Low FT3, low FT4, and low TSH were
present in 21.03%, 15.9% and 4.5% of patients,
respectively. Pattern corresponding to sick euthyroid syndrome was the most
common. Both mean FT3 and FT3/FT4 ratio decreased with increasing
severity of COVID-19 illness (p=0.001). In multivariate analysis, low
FT3 was associated with increased risk of mortality (OR 12.36, 95% CI:
1.23–124.19; p=0.033). Thyroid autoantibodies were positive in
58 (27.14%) patients; but it was not associated with any thyroid
dysfunction. Thyroid function abnormality is common among COVID-19 patients.
Both low FT3 and FT3/FT4 ratio are indicators of disease severity while
low FT3 is a prognostic marker of COVID-19 associated mortality.
Key words
SARS-CoV2 - low FT3 syndrome - mortality - sick euthyroid syndrome - thyroiditis
