[Case report: persistent fever after SARS-CoV-2 infection]

Long-Term Impacts of COVID-19 on Thyroid Health: Insights From Clinical Studies

BACKGROUND

COVID-19 emerged in December 2019 and rapidly became a global pandemic. It has since been associated with the progression of various endocrine disorders, including thyroid disease. The long-term effects of this interplay have yet to be explored. This review explores the relationship between COVID-19 and thyroid diseases, emphasizing thyroid gland function and the clinical implications for managing thyroid disorders in infected individuals.

OBJECTIVES

This narrative review intends to provide insight into the scope of research that future clinical studies may aim to address regarding the long-term effects of COVID-19 infection on thyroid health.

METHODS

Keywords including "thyroid disease", "COVID-19", and "long-term" were used to search PubMed and Google Scholar for updated and relevant clinical research.

RESULTS

COVID-19 affects the thyroid gland multifacetedly and includes direct viral invasion, immune-mediated damage, and hypothalamic-pituitary-thyroid axis disruption. Approximately 15% of COVID-19 patients experience thyroid dysfunction, which can present as thyrotoxicosis, hypothyroidism, or non-thyroidal illness syndrome (NTI). Noteworthy findings include inflammatory thyroiditis. Long-term effects, including those observed in children, include persistent hypothyroidism and exacerbated pre-existing thyroid-autoimmune conditions. Management of thyroid disorders in COVID-19 patients requires consideration: anti-thyroid drug (ATD) therapy used to treat hyperthyroidism in COVID-19 patients may need adjustment to prevent immunosuppression. Radioactive iodine (ROI) alternatives and interleukin-6 (IL-6) receptor antagonists could offer potential benefits and should be further explored.

CONCLUSION

Longitudinal follow-ups post-COVID-19 for patients with new and pre-existing thyroid disorders can improve disease outcomes. In addition, pathophysiological research on thyroid dysfunction in COVID-19 may help develop strategies to prevent and alleviate thyroid gland abnormalities post-COVID-19.

Subacute thyroiditis following COVID-19: A systematic review

Background

Subacute thyroiditis (SAT) is a self-limiting thyroid inflammatory disease occurring specifically after upper respiratory tract infections. Since COVID-19 is a respiratory disease leading to multi-organ involvements, we aimed to systematically review the literature regarding SAT secondary to COVID-19.

Methods

We searched Scopus, PubMed/MEDLINE, Cochrane, Web of Science, ProQuest, and LitCovid databases using the terms "subacute thyroiditis" and "COVID-19" and their synonyms from inception to November 3, 2022. We included the original articles of the patients with SAT secondary to COVID-19. Studies reporting SAT secondary to COVID-19 vaccination or SAT symptoms' manifestation before the COVID-19 infection were not included.

Results

Totally, 820 articles were retained. Having removed the duplicates, 250 articles remained, out of which 43 articles (40 case reports and three case series) with a total of 100 patients, were eventually selected. The patients aged 18-85 years (Mean: 42.70, SD: 11.85) and 68 (68%) were women. The time from the onset of COVID-19 to the onset of SAT symptoms varied from zero to 168 days (Mean: 28.31, SD: 36.92). The most common symptoms of SAT were neck pain in 69 patients (69%), fever in 54 (54%), fatigue and weakness in 34 (34%), and persistent palpitations in 31 (31%). The most common ultrasonographic findings were hypoechoic regions in 73 (79%), enlarged thyroid in 46 (50%), and changes in thyroid vascularity in 14 (15%). Thirty-one patients (31%) were hospitalized, and 68 (68%) were treated as outpatients. Corticosteroids were the preferred treatment in both the inpatient and outpatient settings (25 inpatients (81%) and 44 outpatients (65%)). Other preferred treatments were nonsteroidal anti-inflammatory drugs (nine inpatients (29%) and 17 outpatients (25%)) and beta-blockers (four inpatients (13%) and seven outpatients (10%)). After a mean duration of 61.59 days (SD: 67.07), 21 patients (23%) developed hypothyroidism and thus, levothyroxine-based treatment was used in six of these patients and the rest of these patients did not receive levothyroxine.

Conclusion

SAT secondary to COVID-19 seems to manifest almost similarly to the conventional SAT. However, except for the case reports and case series, lack of studies has limited the quality of the data at hand.

The New Entity of Subacute Thyroiditis amid the COVID-19 Pandemic: From Infection to Vaccine

This is a review of full-length articles strictly concerning subacute thyroiditis (SAT) in relation to the SARS-CoV-2 virus infection (SVI) and COVID-19 vaccine (COV) that were published between the 1st of March 2020 and the 21st of March 2022 in PubMed-indexed journals. A total of 161 cases were reported as follows: 81 cases of SAT-SVI (2 retrospective studies, 5 case series, and 29 case reports), 80 respective cases of SAT-COV (1 longitudinal study, 14 case series, 17 case reports; also, 1 prospective study included 12 patients, with 6 patients in each category). To our knowledge, this represents the largest cohort of reported cases until the present time. SAT-SVI was detected in adults aged between 18 and 85 years, mostly in middle-aged females. SAT-COVID-19 timing classifies SAT as viral (synchronous with infection, which is an original feature of SATs that usually follow a viral infection) and post-viral (during the recovery period or after infection, usually within 6 to 8 weeks, up to a maximum 24 weeks). The clinical spectrum has two patterns: either that accompanying a severe COVID-19 infection with multi-organ spreading (most frequent with lung involvement) or as an asymptomatic infection, with SAT being the single manifestation or the first presentation. Either way, SAT may remain unrecognized. Some data suggest that more intense neck pain, more frequent fever, and more frequent hypothyroidism at 3 months are identified when compared with non-SAT-SVI, but other authors have identified similar presentations and outcomes. Post-COVID-19 fatigue may be due to residual post-SAT hypothyroidism. The practical importance of SAT-SVI derives from the fact that thyroid hormone anomalies aggravate the general status of severe infections (particular concerns being tachycardia/arrhythmias, cardiac insufficiency, and ischemic events). If misdiagnosed, SAT results in unnecessary treatment with anti-thyroid drugs or even antibiotics for fever of unknown cause. Once recognized, SAT does not seem to require a particular approach when compared with non-COVID-19 cases, including the need for glucocorticoid therapy and the rate of permanent hypothyroidism. A complete resolution of thyroid hormone anomalies and inflammation is expected, except for cases with persistent hypothyroidism. SAT-COV follows within a few hours to a few weeks, with an average of 2 weeks (no particular pattern is related to the first or second vaccine dose). Pathogenesis includes molecular mimicry and immunoinflammatory anomalies, and some have suggested that this is part of ASIA syndrome (autoimmune/inflammatory syndrome induced by adjuvants). An alternative hypothesis to vaccine-related increased autoimmunity is vaccine-induced hyperviscosity; however, this is supported by incomplete evidence. From what we know so far concerning the risk factors, a prior episode of non-SVI-SAT is not associated with a higher risk of SAT-COV, nor is a previous history of coronavirus infection by itself. Post-vaccine SAT usually has a less severe presentation and a good outcome. Generally, the female sex is prone to developing any type of SAT. HLA susceptibility is probably related to both new types of SATs. The current low level of statistical evidence is expected to change in the future. Practitioners should be aware of SAT-COV, which does not restrict immunization protocols in any case.