Long COVID in Patients with Mild to Moderate Disease: Do Thyroid Function and Autoimmunity Play a Role?, 2021, Lui et al

Highlights

• 20% had long COVID at 3 months after recovery from non-severe acute illness
• Female and higher SARS-CoV-2 viral load on presentation predicted long COVID
• Incident thyroid dysfunction was rare, but incident anti-TPO positivity was noted
• Symptom resolution was more likely in those with positive anti-TPO upon follow-up

Abstract

Objective
Long COVID (LC) is an emerging global health issue. Fatigue is a common feature. Whether thyroid function and autoimmunity play a role is uncertain. We aimed to evaluate the prevalence and predictors of LC and the potential role of thyroid function and autoimmunity in LC.

Methods
We included consecutive adults without known thyroid disorder, admitted to a major COVID-19 centre for confirmed COVID-19 from July to December 2020 who had thyroid function tests (TFTs) and anti-thyroid antibodies measured on admission and at follow-up. LC was defined by the presence or persistence of symptoms upon follow-up.

Results
In total, 204 patients (median age: 55.0 years; 46.6% men) were reassessed at a median of 89 days (IQR: 69–99) after acute COVID-19. Forty-one (20.1%) had LC. Female (adjusted odds ratio [aOR] 2.48, p=0.018) and SARS-CoV-2 PCR cycle threshold value <25 on admission (aOR 2.84, p=0.012) independently predicted the occurrence of LC. Upon follow-up, most abnormal TFTs in acute COVID-19 resolved, and incident thyroid dysfunction was rare. Nonetheless, we observed incident anti-TPO (anti-thyroid peroxidase) positivity. While baseline or follow-up TFTs were not associated with the occurrence of LC, among 172 patients symptomatic in acute COVID-19, symptom resolution was more likely in those with positive anti-TPO upon follow-up (p=0.043).

Conclusion
LC is common among COVID-19 survivors, with female and those with higher viral load in acute COVID-19 particularly vulnerable. The observation of incident anti-TPO positivity warrants further follow-up for thyroid dysfunction. Whether anti-TPO plays a protective role in LC remains to be elucidated.

Open access, https://www.endocrinepractice.org/article/S1530-891X(21)01111-3/fulltext