Does COVID-19 infection change thyroid hormone levels? A comparative cross-sectional study in Iran

Background: Given the paucity of research investigating the changes of thyroid hormones in people affected with COVID-19, this study aimed to evaluate the levels of thyroid hormones in people affected by COVID-19 infection in Ahvaz, Iran. Methods: : 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 and one month after recovery and in participants without infection. Data were analyzed using paired t-test, Wilcoxon test, and ANCOVA. Results: : 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 <.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 =.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 =.076) that was reduced in the follow-up period. Thirty-five (44.8%) patients had severe disease and were admitted to ICU, that nine of them have died. The level of TSH was non- significantly lower in patients with severe disease compared to those with moderate disease. Conclusion: Patients with COVID-19 infection showed abnormalities in thyroid hormones such as decreased levels of TSH. Patients with severe disease had a lower level of TSH. More investigation about thyroid function in patients with COVID-19 are recommended.