De Quervain thyroiditis (subacute granulomatous thyroiditis) is often triggered by a viral infection. Patients may present with painful thyroid enlargement, elevated inflammatory markers, and transient hyperthyroidism. Hashimoto’s and Graves' diseases are autoimmune in nature.

According to Braverman’s The Thyroid:

“Subacute (De Quervain) thyroiditis typically follows a viral upper respiratory tract infection and is characterized by thyroid pain and transient thyrotoxicosis.”