Factors affecting recurrence in subacute granulomatous thyroiditis.

Objective: This study aimed to evaluate the factors affecting recurrence in subacute granulomatous thyroiditis (SAT). Methods: A total of 137 patients with SAT were enrolled in the study; 98 (71.5%) were women and 39 (28.5%) were men. The patients received either steroid or nonsteroidal anti-inflammatory drug (NSAID) for eight weeks. Erythrocyte sedimentation rate (ESR), C-reactive protein, serum thyroid-stimulating hormone (TSH), free triiodothyronine, free thyroxine (FT4), anti-thyroid peroxidase antibodies and thyroglobulin antibodies, neutrophil, lymphocyte, platelet, neutrophil to lymphocyte ratio, and platelet to lymphocyte ratio levels were evaluated. In addition, recurrence rates were compared between patients who received NSAID treatment and those who received steroid therapy. Results: Treatment modality and pretreatment TSH, FT4, and ESR were significantly different between patients with and without recurrence (p = 0.011, 0.001, 0.004, and 0.026, respectively). Compared with patients without recurrence, those with recurrence had higher pretreatment TSH levels, but lower FT4 and ESR levels. On logistic regression analysis, treatment modality was found to be an independent risk factor for recurrence. The risk of recurrence was higher in those taking steroids than in those taking NSAIDs (p = 0.015). The optimal TSH cutoff value for recurrence was 0.045 µIU/mL, with a sensitivity of 83.3% and specificity of 76% (AUC 0.794, 95% CI 0.639-0.949). Conclusion: The risk of SAT recurrence was higher with steroid therapy than with NSAIDs. Patients who had mild thyrotoxicosis had relatively high recurrence rate and may need a relatively longer duration of treatment.