Long-term thyroid dysfunction is unlikely following hospitalization for severe COVID-19 infection, according to results of a study published in European Thyroid Journal.
Severe COVID-19 infection may interfere with typical thyroid functioning, but long-term effects are largely unknown.
Researchers conducted a single-center observational study between March 2020 and May 2021 to evaluate changes in thyroid dysfunction following severe COVID-19 infection. Correlations between COVID-19 disease severity and thyroid dysfunction detected were analyzed among patients who survived infection. Patients were observed for 1 year and invited to attend follow-up visits at 2, 3, 6, and 12 months after hospital discharge. Associations between thyroid dysfunction and COVID-19 disease severity were assessed via Fisher exact testing or Spearman correlation.
The final analysis included 183 patients with no history of thyroid disease. The mean (SD) patient age was 67.5 (13.8) years, and 124 (68%) patients were men.
A total of 75 patients agreed to attend at least 1 follow-up visit, of whom 65% were men. Baseline concentrations of serum thyrotropin and free thyroxine (FT4) among these patients were similar when compared with those of the overall study population, but free triodothyronine (FT3) concentrations were higher.
Ultrasonography results captured from 65 patients after discharge showed focal hypoechoic areas suggestive of thyroiditis in 28%. Further analysis showed focal hypoechogenicity was significantly correlated with low thyrotropin (P =.034), high FT4 (P =.018), and high interleukin-6 levels (P =.016) at baseline. In patients with available follow-up data captured at 6 (n=15) and 12 (n=12) months, areas of focal hypoechogenicity had persisted in 87% and 50%, respectively, but were often reduced in size.
The prevalence of thyroid autoantibodies and thyrotropin concentrations did not significantly differ between patients with and without areas of focal hypoechogenicity found on ultrasonography.
“Focal areas of hypoechogenicity suggestive of thyroiditis, however, were still observed in the thyroid gland up to 1 year after hospital discharge, albeit less evident and not apparently related to thyroid autoimmunity,” the researchers noted.
Study limitations include the lack of thyroglobulin measurement during hospitalization and insufficient data on serum FT3 and FT4 concentrations for some patients. In addition, time to first thyroid ultrasonography following initial COVID-19 diagnosis was delayed and due to restricted hospital access during the COVID-19 pandemic.
“In this study population, Covid-19-induced thyroid dysfunction was transient, with nearly all patients recovering to normal thyroid function as soon as 3 months post-infection,” the researchers concluded.
Muller I, Daturi A, Varallo M, et al. Long-term outcome of thyroid abnormalities in patients with severe COVID-19. Eur Thyroid J. Published online January 30, 2023. doi:10.1530/ETJ-22-0200