1. Fever of Unknown Origin
Domenick Roma
7/31/2009

2. Types
Classic FUO
Nosocomial FUO
Immune-deficient FUO
HIV-related FUO

3. Definition Fever higher than 38.3ºC on several occasions
Duration of fever for at least three weeks
Uncertain diagnosis after one week of study in the hospital
Uncertain diagnosis after 3 outpatient visits or three days of study in the hospital.

4. History

5. Physical Exam Facial/Sinus Tenderness  Sinusitis
Temporal Artery Tenderness Temporal Arteritis
Tenderness of a Tooth  Periapical Dental Abscess
Roth Spots on Fundoscopic Exam Endocarditis
Enlarged Tender Thyroid  Thyroiditis
Murmur  Endocarditis
Perirectal Tenderness/Fluctuance  Perirectal Abscess
Prostatic Tenderness  Prostatitis or Prostate Abscess
Splenomegaly  Lymphoma, Endocarditis, Leishmaniasis
Lymphadenopathy  Lymphoma, HIV, Tuberculosis
Calf Tenderness  DVT

6. Approach to Diagnosis
Erythrocyte sedimentation rate (and/or C-reactive protein)
Antinuclear antibodies
Rheumatoid factor
Angiotensin-converting enzyme
Cytomegalovirus IgM antibodies or virus detection in blood
Heterophile antibody test in children and young adults
Mantoux skin test
CT scan of abdomen (or radionuclide scan)
HIV antibody test
Comprehensive History
Physical Examination
Complete blood count, including differential and platelet count
Blood cultures (three sets drawn without administering antibiotics)
Routine blood chemistries, including liver enzymes and bilirubin
Hepatitis serologies (if liver tests abnormal)
Urinalysis, including microscopic examination, and urine culture
Chest radiograph

7. Invasive Testing Liver Biopsy Lymph Node Biopsy
Bone Marrow Biopsy/Culture
Temporal Artery Biopsy
Exploratory Laparotomy

8. Causes

9. Causes Infectious (16%) Malignancies (7%)
TB, Abscess, Endocarditits, Osteomyelitis, Dental Abscess
Malignancies (7%)
Lymphoma, Leukemia, Renal Cell Carcinoma, Liver (HCC or metastases)
Connective Tissue Disease (22%)
Adult Stills Disease, Temporal Arteritis, polyarteritis nodosa, Takayasu's arteritis, Wegener's, mixed cryoglobulinemia
Other (4%)
DVT, Drugs, Factitious, Hypothalmic Dysfunction, Hereditary Fever Syndromes
Undiagnosed (51%)

10. Treatment & Prognosis Treatment Prognosis Empiric antibiotics?
Trial of Steroids?
Prognosis
Depends on final diagnosis
Undiagnosed generally have good prognosis

11. References Clinical Medicine 2008 Oct 8 (5): 526-530.
Arch Intern Med Mar 10;163(5):
Am Fam Physician Dec 1;68(11):
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