Subacute Thyroiditis Presenting as Fever of Unknown Origin

Abstract

Background: Subacute thyroiditis (SAT) is a rare but well-established cause of fever of unknown origin (FUO) and should be considered in the differential of patients presenting with fever of unknown origin. Few reports in the English literature where published about Subacute thyroiditis manifesting as fever of unknown origin. Subacute thyroiditis may be hard to detect by physicians based on history and physical exam if the systemic manifestations are absent. Methods: An observational retrospective review of 375 charts of patients presenting with thyroiditis to the American University of Beirut Medical Center between January 1995 and June 2015. Inclusion criteria included patients who have subacute thyroiditis based on the American Thyroid Association and American Association of Clinical Endocrinologists guidelines and fever of unknown origin based on Durak and Street’s definition. All patients that do not fit both inclusion criteria were excluded. The patients’ demographics, clinical presentation, laboratory and diagnostic findings, and treatments used were analyzed. Results: 375 charts were reviewed. 31 patients had SAT of which 13 patients had fever of unknown origin before diagnosing subacute thyroiditis. 13 charts were not available for screening. Symptoms of hyperthyroidism including palpitations, neck tenderness and weight loss were not present in all patients. Elevated markers of inflammation mainly ESR and CRP were raised when screened for.Conclusions: The diagnosis of subacute thyroiditis should be considered in patients presenting with fever of unknown origin and elevated inflammatory markers, even in the absence of suggestive clinical symptoms.