The prognostic significance of thyroid functions on the length of ICU and hospital stay of COVID-19 patients

Background: Since, the thyroid gland is affected both due to the cytokine storm and via angiotensinconverting enzyme-2 receptors, changes in thyroid functions can be among the prognostic factors of COVID-19 patients (1,2). The aim of this study is to evaluate the prognostic significance of thyroid functions at COVID-ICU admission. Method: After ethical approval, PCR (+) COVID-19 patients followed in the ICU between March 2020 and April 2021 were retrospectively screened. Patients with previous thyroid disease were excluded from the study. Free triiodothyronine (fT3 free thyroxine (fT4 and thyroid-stimulating hormone (TSH) levels at ICU admission were evaluated. Mann Whitney U, Spearman correlation, binary logistic, and linear regression tests were used for statistical analysis. Results: A total of 131 patients (46 female, 85 male) were included in the study (Fig 1). The the 90- day mortality rate was 46%. There was no statistically significant relationship between thyroid function levels and mortality. Significant correlations were found between age, APACHE II, fT3, C-reactive protein and duration of ICU (r:0,236, p:0,002;r:0,262, p:0,004;r:-0,271, p:0,011;r:0,277, p:0,001 respectively) and hospital stay (r:0,193, p:0,027;r:0,177, p:0,054;r:-0,326, p:0,002;r:0,198, p:0,023, respectively). Linear regression analysis revealed fT3 as the only independent predictor for ICU (β:- 0,259, p:0,036) and hospital stay (β:-2,138, p:0,036). Conclusion: Free triiodothyronine levels at ICU admission can predict the length of ICU and hospital stay in COVID-19 patients. (Table Presented).