Thyroid Stimulating Hormone as a Possible Additional COVID-19 Outcome Marker

Background and Objectives: The interaction between thyroid and SARS-CoV-2 is complex and not yet fully understood. This study aimed to identify a predictive value of serum TSH levels on the short-term and middle-term outcomes of patients hospitalized for COVID-19. Materials and Methods: We retrospectively analyzed electronic records (ERs) data for hospitalized COVID-19 patients between March 2020 and June 2021 and their ERs during outpatient visits, 6-8 weeks post-discharge, in cases of known serum TSH levels and no previous thyroid disorder. The short-term (length of hospital stay, MSCT findings of lung involvement, required level of oxygen supplementation, admission to the ICU, and death) and middle-term outcomes after 6 to 8 weeks post-discharge (MSCT findings of lung involvement) were analyzed. Results: There were 580 patients included: 302 males and 278 females, average age of 66.39 ± 13.31 years, with no known thyroid disease (TSH mean 1.16 ± 1.8; median 0.80; no value higher than 6.0 mIU/L were included). Higher TSH was observed in patients with less severe outcomes and was associated with significantly higher SpO₂ during hospitalization. Patients who required overall more oxygen supplementation or HFOT, mechanical ventilation, and patients who were more frequently admitted to the ICU or were more often treated with corticosteroids had lower TSH than those who did not show these indicators of disease severity. Lower TSH was also present in non-survivors when compared to survivors (all p < 0.01). Patients with low TSH during hospitalization more often had persistent lung involvement during the post-COVID-19 period (p = 0.028). In the post-COVID-19 period, there was an overall, statistically significant increase in the TSH levels when compared to TSH during hospitalization (p < 0.001). Conclusions: Low/suppressed serum TSH levels during acute COVID-19 may be an additional laboratory test that should be included in the prediction of unfavorable short- and middle-term outcomes.