Thyroid Health Following a COVID-19 Infection

June 7, 2023

Research on COVID-19 and thyroid health has indicated a connection between acute COVID-19 and thyroid dysfunction. However, there has been a lack of information regarding the long-term effects of a COVID-19 infection on the thyroid. 

Authors of a recent scientific paper investigated thyroid function, autoimmunity, the occurrence of long COVID, and the effect of interferon beta-1b treatment among 250 COVID-19 patients for six months after infection. Researchers used thyroid function tests and anti-thyroid antibody titer measures (measurement of antibody levels) during the acute COVID-19 phase, as well as three and six months after. 

Results showed that patients with abnormal thyroid function test results during the acute phase of a COVID-19 infection are more likely to have persistent thyroid function abnormalities. However, most abnormalities resolved during the follow-up period (82.4%). For patients with normal thyroid function test results during acute-infection, only a small fraction (4.5%) exhibited abnormal thyroid function tests at the three or six month mark. While most patients did not exhibit a change in anti-thyroid antibody levels during the six-month follow-up period, interferon-treated patients did show a slight increase in the anti-thyroid antibody levels. This was the case with the 4.5% of patients who exhibited abnormal thyroid function during follow-up. These numbers suggest that SARS-CoV-2 infection does not lead to significant thyroid dysfunction. 

Researchers also observed an increased prevalence of long Covid amongst this patient cohort, with 19.5% and 10.4% of patients experiencing long Covid symptoms at three and six months post-acute infection, respectively. That being said, results of thyroid function tests and anti-thyroid antibody titers did not influence the occurrence of long COVID. 

Authors point out that most patients who took part in the study experienced mild-to-moderate COVID-19 symptoms, making results relevant to a wider population. However, this also points to the limitations. For example, results may not apply to all COVID-19 variants since most patients included in the study were infected with the original strain. Additionally, the subgroups analyzed in the study were relatively small, thus warranting additional research with a bigger, more diverse group of participants. 

Authors agree with current recommendations that thyroid function monitoring is unnecessary after a COVID-19 infection, unless patients are being treated with interferon beta-1b or experienced thyroid function abnormalities during acute-infection.