Inpatient / Infectious DIsease

Fever of Unknown Origin (FUO)

Last Updated: 1/18/2023

# Fever of Unknown Origin

Fevers >3 weeks without an obvious cause - usually assumes you've done a first pass at a basic workup

-- History: *** fever pattern, B symptoms, travel, animal exposures, sick contacts, sexual contact, drugs, occupation, TB RFs, family history
-- Clinical/Exam: *** dental caries, murmur, abd tenderness, lymph nodes, joints, skin/nails
-- Data: *** initially - CBC/diff, BMP, LFTs, ESR/CRP, UA/UCx, BCx, CXR as a first pass

-- Rheum - vasculitits (GCA, ANCA-associated), Takayasu, Adult Still’s, SLE)
-- Infectious - endocarditis, osteomyelitis, liver/abdominal abscess, tickborne, TB, Q fever, brucellosis
-- Malignancy - lymphoma, RCC, HCC
-- Drug Fever - abx, AEDs, precedex, chemo
-- Other - alc hep, clotting, hyperthyroidism

The patient's HPI is notable for ***. Exam showed ***. Labwork and data were notable for ***. Taken together, the patient's presentation is most concerning for ***, with a differential including ***.

-- Initial labs - CBC/diff, peripheral smear, BMP, LFTs, ESR/CRP, UA/UCx, BCx, CXR
-- Deep Cuts - HIV, RPR, SPEP/SFLC, ANA, RF/CCP, ANCA, cryoglobulins, CK/aldolase, EBV, CMV, ferritin, HBV/HCV
-- Imaging - pan scan, TTE, FDG-PET

-- Avoid abx unless hemodynamically unstable or immunocompromised
-- Trial peeling off meds - drug fever is dx of exclusion

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Infectious Causes of Fever of Unknown Origin (Clin Med Lond, 2015)