Demonstration of diagnosis, treatment, prognosis and recurrence rates in patients with subacute thyroiditis

Objective: Subacute thyroiditis (SAT) is an inflammatory thyroid disorder that frequently develops following viral infections. Although it is generally self-limiting, some cases may progress with recurrences or permanent hypothyroidism. The aim of this study was to retrospectively evaluate the clinical, laboratory, and radiological findings of patients diagnosed with subacute thyroiditis and to identify risk factors associated with recurrence and the development of permanent hypothyroidism. Materials and Methods: This retrospective study included 79 patients diagnosed with subacute thyroiditis between 2017 and 2023. Demographic data, clinical characteristics, laboratory parameters (TSH, free T4, free T3, CRP, ESR, etc.), treatment protocols (use of steroids or NSAIDs), and ultrasonography and radioactive iodine uptake test findings of the patients were obtained from medical records. Patients were evaluated in terms of recurrence and permanent hypothyroidism after treatment, and potential risk factors were analyzed using statistical methods. Results: Recurrence was observed in approximately one-third of patients (34.2%), while permanent hypothyroidism developed in 11.4%. Female sex was identified as a significant risk factor for recurrence. Although recurrence rates were higher among patients receiving steroid therapy, no significant association was found between steroid use and the development of permanent hypothyroidism. Elevated TSH levels at diagnosis emerged as a predictive parameter for recurrence. Ultrasonographic findings (hypoechoic areas, vascularity changes) and radioactive iodine uptake test results were not significantly associated with recurrence or permanent hypothyroidism. Conclusion: In patients with subacute thyroiditis, recurrence and permanent hypothyroidism are related to both clinical and laboratory parameters, with treatment choice being one of the most important determinants of prognosis. Female sex and steroid therapy were found to be significantly associated with an increased risk of recurrence, but not with the development of permanent hypothyroidism; our study does not support a protective effect against persistent hypothyroidism. Elevated TSH levels at diagnosis may serve as a valuable marker for predicting long-term prognosis. These findings provide guidance for clinicians in patient management and contribute to the development of more individualized treatment strategies. Keywords: Subacute thyroiditis, Recurrence, Permanent hypothyroidism, Steroid therapy, TSH level