Management Approach in Coexisting Subacute Thyroiditis and Graves’ Disease: A Case Report

Subacute thyroiditis and Graves’ disease are both common causes of thyrotoxicosis, yet their coexistence is rare and poses unique diagnostic and therapeutic challenges. We report a case of a 64-year-old man who presented with symptoms and imaging findings consistent with subacute thyroiditis, alongside elevated thyroid-stimulating and TSH receptor antibodies suggestive of Graves’ disease. Initial treatment with prednisolone and a standard methimazole dose led to resolution of inflammation but resulted in hypothyroidism, necessitating methimazole withdrawal and later resumption at a lower dose. The patient subsequently remained euthyroid on long-term low-dose therapy, with no recurrence of subacute thyroiditis. This case highlights the importance of recognizing overlapping thyroid pathologies and the potential need for conservative antithyroid drug dosing to avoid overtreatment during recovery from inflammatory thyroid destruction. • Coexisting subacute thyroiditis and Graves’ disease present a diagnostic challenge • High free T4 guided initial dual therapy with prednisolone and methimazole • Conservative methimazole dosing may help avoid post-inflammatory hypothyroidism