Fever of Unknown Origin as a Sole Presentation of Subacute Thyroiditis in an Elderly Patient: A Case Report with Literature Review

Abstract

An 80-year-old Caucasian male presented with fever of 3-week duration. Outpatient workup for infectious etiologies was negative and due to persistent fever, he was hospitalized for further evaluation of fever of unknown origin (FUO). Physical examination and laboratory studies remained unremarkable; however a follow-up CT scan of chest, abdomen, and pelvis with contrast done to rule out malignancy as an underlying cause of FUO revealed heterogeneous thyroid gland with surrounding hazy changes suggestive of thyroiditis. Thyroid function tests confirmed the diagnosis of subacute thyroiditis. The patient was started on prednisone with good response in his symptoms and was eventually discharged to home. The importance of our case lies in the fact that diagnosing subacute thyroiditis in the absence of classical symptoms of neck pain can be challenging and a physician should have a very high index of suspicion especially in an elderly patient where FUO can be the sole presentation.

Fever of unknown origin as the major manifestation of subacute thyroiditis

“…Most patients with SAT have negative antithyroglobulin antibodies and antithyroid peroxidase antibodies as opposed to painless thyroiditis in which 50% of patients have positive antibodies (3,11). Both antibodies were negative in our case, making silent thyroiditis less likely.…”

“…thyroid storm, adrenal crisis, and pheochromocytoma). However, FUO as the sole presenting feature is very rare with only a few reported cases in the literature ( 1 , 3 ). The endocrine disorder most likely to present as an FUO is subacute thyroiditis (SAT); however, telltale findings in these reported cases often point to this disorder ( 4 , 5 ).…”

“…Also termed granulomatous, giant cell, or de Quervain thyroiditis, SAT accounts for about 5% of thyroid disorders ( 2 , 3 ). The annual incidence is 4.9 cases per 100,000/year, the peak incidence occurs at 30 to 50 years of age, and the female to male ratio is 3-5:1.…”

Subacute Thyroiditis Presenting as Fever of Unknown Origin

“…In fact, one study showed superiority of steroid use in SAT in patients who fail to achieve clinical remission with NSAIDs 22 . Long term follow-up of patients presenting with SAT is needed to assess for development of permanent hypothyroidism which may occur post transient thyrotoxicosis in around 25 percent of patients requiring treatment with levothyroxine 23 .…”

Successful Management of Pheochromocytoma and Thyroiditis With Fever by Telemedicine During the COVID-19 Pandemic

“…The patient’s daughter was very involved in the care. At the first telemedicine session, I discussed that fever can be the main or even the only symptom of subacute thyroiditis but occult infections have to be further ruled out before corticosteroid treatment is initiated ( 3 ). As he did not respond to ibuprofen and propranolol and I could not do a physical examination, I ordered a fluorodeoxyglucose positron emission tomography (FDG PET) and thyroid ultrasound, otherwise not required for subacute thyroiditis diagnosis and management, which were done on the next day.…”