does covid-19 infection change thyroid hormone levels? a comparative cross-sectional study in iran

Background: there is a paucity of research investigating the changes in thyroid hormones in individuals affected by coronavirus disease 2019 (covid-19). objectives: this study aimed to evaluate the levels of thyroid hormones in individuals 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 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). 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 < 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. conclusions: 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.