THYROXIN AND THYROID-STIMULATING HORMONE CHANGES IN PATIENTS WITH COVID-19

Sanem Kayhan^{1, *}, Nazli Gulsoy Kirnap²

¹Department of Internal Medicine, University of Health Sciences, Diskapi Yildirim Beyazit Training and Research Hospital, Ankara, Turkey - ²Department of Endocrinology and Metabolism, Baskent University Faculty of Medicine, Ankara, Turkey

Objective: 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.