Subacute Thyroiditis Without Neck Pain: An Unusual Cause of Persistent Fever in the Elderly Patient.

Subacute thyroiditis can present as fever of unknown origin, particularly in elderly patients. Absence of neck pain or thyroid tenderness does not exclude the diagnosis. Thyroid function tests and inflammatory markers are key to diagnosis. Corticosteroids lead to rapid symptomatic improvement in moderate-to-severe cases. A transient hypothyroid phase is common and often resolves without long-term thyroxine therapy.