Thyroid Dysfunction After COVID-19 Infection

Cureus recently published a retrospective study on thyroid disruption following COVID-19 infection. While SARS-CoV-2 is known to affect the respiratory system, the virus can also attack the cardiovascular, nervous, and gastrointestinal systems within the body, including the thyroid. Thyroid follicular cells have ACE2 and TMPRSS2 receptors that facilitate the invasion of SARS-CoV-2, triggering an inflammatory cascade and hyperactive immune response. Immune-mediated mechanisms, namely cytokines such as IL-6 and IL-1β, have been shown to suppress the hypothalamic-pituitary-thyroid axis and alter thyroid hormone metabolism.

The University of Missouri conducted a single-center retrospective study of 615 adults with confirmed COVID-19 infection and thyroid function tests between March 2020 and December 2023. Patients with pre-existing thyroid conditions or on medications that affect the thyroid were excluded; “thyroid dysfunction was defined as any abnormality in TFTs [thyroid function tests].”

Eighty-four patients (13.6%) had thyroid dysfunction involving direct viral effects and systemic inflammatory responses. The largest group presented as non-thyroidal illness syndrome (NTIS; 39 patients), followed by subclinical hypothyroidism (37), overt hyperthyroidism (6), and overt hypothyroidism (2).

Cases were followed for around one year by chart review; overt progression was noted among 7% of individuals with subclinical hypothyroidism, while 21% of patients with NTIS returned to normal thyroid levels. The authors note that these findings are consistent with other reports showing normal thyroid function 12 months post-COVID-19 infection and no increase in thyroid autoimmunity markers. “Such transient abnormalities may reflect an adaptive endocrine response to acute illness, rather than a sign of permanent dysfunction.” They add that the potential for autoimmune thyroid disease post-COVID-19 infection, particularly Graves’ disease, is still being explored.

Citation

Tadisina, S., Mohammed, S., Asad, R., Tselovalnikova, T., Nguyen, B., Akella, P. V., & Abu Kishk, M. (2025). Prevalence and Evolution of Thyroid Dysfunction in COVID-19: A Retrospective Study. Cureus, 17(9), e93542. https://doi.org/10.7759/cureus.93542