Kayhan, SanemKirnap, Nazli Gulsoy2022-12-122022-12-1220220393-6384http://hdl.handle.net/11727/8260Objective: Whether COVID-19 has any effect on thyroid function is still up for debate. The aim of this study was to assess thyroid function in COVID-19 patients. Materials and methods: Clinical signs, laboratory results, and computed tomography scans of the chest of patients followed up in our hospital due to COVID-19 infection, who did not have a known history of thyroid disease, were analyzed retrospectively. Prior to the initiation of treatment for COVID-19 infection, a total of 131 patients who underwent thyroid function tests and 70 healthy volunteers were included in the study as the control group. Serum free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels of COVID-19 and control groups were measured and compared. Results: When compared with the healthy control group, within the normal range, COVID-19 patients had a significantly lower TSH level and significantly higher fT4 level (p=0.001, p < 0.001, respectively). When each group was compared with the control group in terms of clinical severity, it was found that TSH levels were significantly lower in the critical case group (p < 0.001), and fT4 levels were significantly higher in all levels of clinical severity of COVID-19 (mild to critical) (p < 0.001, p < 0.001, p=0.001, and p=0.006, respectively). Conclusion: Although TSH and fT4 levels were within the normal range in COVID-19 infection, they changed significantly. This suggests that the changes in thyroid function tests in COVID-19 did not have any clinical significance, but caution should be exercised for the transition to thyrotoxicosis in patients with borderline thyroid function tests.enginfo:eu-repo/semantics/closedAccessCOVID-19severitythyroxinthyroid-stimulating hormonearticle3814314350007927977000192-s2.0-85124675761