Remission of Persistent Hypothyroidism Following Subacute Thyroiditis After Discontinuation of Thyroxine: A 9‐Year Retrospective Study

Objective The long‐term outcomes of discontinuing thyroxine replacement therapy in patients with persistent hypothyroidism following subacute thyroiditis are unknown. This study involved an extended follow‐up of a cohort of patients who participated in a clinical trial of prednisone for the treatment of subacute thyroiditis. Methods This retrospective cohort study included 52 patients with moderate to severe scores who were hospitalized between August 2013 and December 2014. Patients previously received prednisone for 1 week, followed by nonsteroidal anti‐inflammatory drugs for 1 week, and prednisone was administered for 6 weeks, after which the patients completed follow‐up to Week 24. Thyroid‐stimulating hormone, free triiodothyronine, and free thyroxine levels of the participants were measured 9 years after enrollment. Results Of the 52 participants randomly assigned to receive prednisone for 1 or 6 weeks, 50 completed the core trial, and 48 were eligible for extended follow‐up, with a median duration of 8.61 years (IQR 8.29−8.77). Thirty participants were assessed at 9 years, 15 could not be contacted, and three refused follow‐up tests. Among the 30 participants, 28 were euthyroid and 2 had subclinical hypothyroidism at 9 years. The median TSH level was 3.46 mIU/L (IQR 2.12–5.15) at 24 weeks and 2.17 mIU/L (IQR 1.83–3.77) at 9 years ( p = 0.001). The median FT4 level was 14.27 pmol/L (IQR 12.15–15.72) at 24 weeks and 15.28 pmol/L (IQR 12.53–16.22) at 9 years ( p = 0.959). Among the three participants diagnosed with persistent hypothyroidism at 24 weeks, one participant was diagnosed with subclinical hypothyroidism without thyroxine replacement therapy at 9 years, and two participants were diagnosed with subclinical hypothyroidism and euthyroidism after gradually withdrawing from thyroxine. Conclusion Thyroid function remains stable in patients with persistent hypothyroidism following subacute thyroiditis after careful dose reduction and discontinuation of thyroxine replacement therapy. This finding may have implications for the individualized management of hypothyroidism.