Subacute thyroiditis is a type of thyroid disease that occurs after a viral infection. This is usually a temporary condition associated with neck pain and may be accompanied by sore throat and flu-like symptoms. We present a case of post COVID-19 subacute thyroiditis and review its presentation and outcome.

Background Graves' disease (GD) is an autoimmune thyroid disorder and recent studies have proposed a role for interleukin (IL)‐37, IL‐38, and vitamin D (VitD) in the pathophysiology of disease. Therefore, this study investigated the expression of IL‐37, IL‐38, and VitD in the serum of GD patients and correlations of their levels with some demographic and clinical characteristics. Methods Serum IL‐37, IL‐38, and VitD levels were evaluated in 90 women with GD and 93 control women using enzyme‐linked immunosorbent assay kits. Depending on therapy, six patients were newly diagnosed (ND; untreated), and 50 patients were receiving only carbimazole (CMZ), while 34 patients were also on CMZ but also received one (31 patients), two (one patient), or three (two patients) doses of radioactive iodine (RAI). Results IL‐37 levels were significantly higher in GD patients than in controls, while IL‐38 and VitD levels were significantly decreased. As indicated by the area under the curve (AUC), receiver operating characteristic curve analysis demonstrated the potential of IL‐37, IL‐38, and VitD as biomarkers to distinguish GD patients from controls (AUC = 0.953, 0.959, and 0.793, respectively). Multinomial logistic regression analysis showed that altered levels of IL‐37, IL‐38, and VitD were most likely associated with the pathogenesis of GD. IL‐37 was negatively correlated with IL‐38 and VitD, while IL‐38 and VitD were positively correlated. Conclusion Serum Il‐37 levels were upregulated in women with GD, while IL‐38 and VitD levels showed downregulated levels. The latter two were positively correlated while they showed a negative correlation with IL‐37.