INTRODUCTION: Multisystem inflammatory syndrome in children (MIS-C) associated with COVID-19 is defined as the presence of documented fever, inflammation, and at least two signs of multisystem involvement and lack of an alternative microbial diagnosis in children who have recent or current SARS-CoV-2 infection or exposure. In this study, we evaluated thyroid function tests in pediatric cases with MIS-C in order to understand how the hypothalamus-pituitary-thyroid axis is affected and to examine the relationship between disease severity and thyroid functions.
METHODS: This case-control study was conducted in our clinic between January 2021 and September 2021. The patient group consisted of 36 MIS-C cases, the control group included 72 healthy children. Demographic features, clinical findings, inflammatory markers, thyroid function tests, and thyroid antibody levels of MIS-C cases were recorded. Thyroid function tests were recorded in the healthy control group.
RESULTS: When MIS-C and healthy control groups were compared in terms of thyroid hormones, free triiodothyronine (FT3) level was lower in MIS-C cases, while free thyroxine (FT4) level was found to be lower in the healthy group (p=<0.001, p=0.001, respectively). Although the FT4 level was statistically significantly lower in the healthy group, no significant difference was found compared with the reference intervals according to age (p=0.318). When compared to the MIS-C cases without intensive care requirement, FT3 levels were also lower in MIS-C cases admitted to the intensive care unit and received steroid treatment (p=0.043, p=<0.001, respectively).
DISCUSSION AND CONCLUSION: In conclusion, since the endocrinological system critically coordinates and regulates important metabolic and biochemical pathways, examination of this system may be beneficial for MIS-C. In our study, low FT3 levels were associated with both the diagnosis of MIS-C and severe clinical presentation. Further studies are needed to predict the prognosis and develop a long-term follow-up management plan.