Does COVID-19 Infection Change Thyroid Hormone Levels? A Comparative Cross-Sectional Study in Iran

 There is a paucity of research investigating the changes in thyroid hormones in individuals affected by coronavirus disease 2019 (COVID-19).

 This study aimed to evaluate the levels of thyroid hormones in individuals affected by COVID-19 infection in Ahvaz, Iran.

 This was a comparative cross-sectional study on 78 patients with COVID-19 infection and 80 individuals without infection. Thyroid-stimulating hormone (TSH), triiodothyronine (TT3), and tetraiodothyronine (TT4) were measured in hospitalized patients at baseline and one month after recovery and in participants without infection. The data were analyzed using a paired t-test, the Chi-square test, the Wilcoxon test, and the analysis of covariance (ANCOVA).

 The level of TSH at baseline in the hospitalized patients was significantly lower than that in the control group (1.24 ± 1.08 vs. 2.05 ± 1.02 mlU/L, respectively, P < 0.0001). The mean level of TT3 was 1.20 ± 0.24 and 1.28 ± 1.25 ng/dL in the case and control groups, respectively (P = 0.188). The level of TT4 in the case group was high at baseline in comparison to the control group (8.48 ± 2.27 vs. 7.76 ± 1.43 ng/dL, P = 0.076), which was reduced in the follow-up period. Thirty-five (44.8%) patients had severe disease and were admitted to the intensive care unit (ICU). The level of TSH was non-significantly lower in patients with severe disease than those with moderate disease.

 Patients with COVID-19 infection showed abnormalities in thyroid hormones, such as decreased levels of TSH and TT3. Patients with severe COVID-19 showed lower levels of TSH and unchanged levels of TT3 and TT4 in comparison to the patients with moderate disease. Further investigation into thyroid function in patients with COVID-19 is recommended.