SHM's Clinical Quick Talks-Approach to Fever of Unknown Origin

Pdf Summary

The approach to a patient with fever of unknown origin (FUO) involves a comprehensive history, physical examination, and appropriate diagnostic testing. There are different categories of FUO, including classic FUO, nosocomial FUO, immune-deficient FUO, and HIV-associated FUO. In the history, it is important to ask about the fever itself, systemic symptoms, localized symptoms, travel history, sick contacts, animal contacts, family history, and sexual history. Potential causes of drug-induced fever should also be considered. The physical examination may reveal findings such as erythema nodosum, heart murmurs, hepatomegaly, joint swelling or pain, livedo reticularis, lymphadenopathy, splenomegaly, temporal artery tenderness, uveitis, and palpable purpura. The initial laboratory testing includes CBC, chemistry panel, liver function tests, ESR, blood cultures, urinalysis, urine culture, and chest x-ray. If the initial tests are negative, a CT scan of the chest, abdomen, and pelvis may be obtained. Further diagnostic testing depends on the suspected cause - if infectious disease is suspected, additional tests may include TTE, sputum culture, HIV test, and serologies for hepatitis A, B, and C. If non-hematologic or hematologic malignancy is suspected, additional tests may include mammography, chest CT, endoscopy, bone scan, lymph node biopsy, and bone marrow biopsy. If rheumatologic disease is suspected, additional tests may include RF, ANA, and temporal artery biopsy. Venous Doppler studies may also be needed in relevant patients. It is important to note that false-positive results in certain tests can lead to unnecessary investigations. Factitious fever should be considered in patients with medical training or experience and a fever persisting longer than six months. In up to 30% of cases, a definitive diagnosis of FUO may not be reached, but patients generally have a favorable outcome.

Asset Subtitle

Patrick Tierney, Trushar Dungarani

Keywords

fever of unknown origin

comprehensive history

physical examination

diagnostic testing

classic FUO

nosocomial FUO

immune-deficient FUO

HIV-associated FUO

drug-induced fever

erythema nodosum