Abstract
Pyrexia of unknown origin (PUO) is not infrequently a diagnostic dilemma for clinicians. Endocrine causes of PUO are rare. The endocrine disorder likely to present as PUO is subacute thyroiditis. Subacute thyroiditis usually occurs in middle-aged women as viral prodrome, classic symptoms of thyrotoxicosis, and an elevated erythrocyte sedimentation rate. The patient may have abrupt onset of fever and chills with complaints of thyroid pain, or only low-grade fever with poorly characterized anterior neck pain. We present a case of PUO in a 40-year-old male who had fever for more than two month. Despite an extensive evaluation, the patient had persistent fever and no cause was found, with the exception of subacute thyroiditis. The fever resolved from the fifth day of treatment with low-dose steroid (Prednisolone, 10mg per day). This case illustrates that subacute thyroiditis should be considered in cases of FUO.