Fever of Unknown Origin Morning Report August 9, 2005 Hili Morillas, MD
Oct 26, 2014
Fever of Unknown Origin
Morning ReportAugust 9, 2005Hili Morillas, MD
Definition Fever > 38.3 on several occasions Fever lasting more than 3 weeks No diagnosis despite 1 week of
inpatient workup
Potential Etiologies Based on patient population Classical Immunodeficient (Neutropenic) Nosocomial HIV related
Classic FUO Fever > 38.3 Duration greater than 3 weeks Evaluation for 3 weeks as an
outpatient or 3 days in hospital
Classic FUO Infection Malignancy Collagen vascular diseases
Nosocomial FUO Fever > 38.3 Patient hospitalized > 24 hours, but
no fever on admission Evaluation for at least 3 days
Nosocomial FUO Clostridium difficile Drug induced Pulmonary embolism Septic thrombophlebitis Sinusitis
Neutropenic FUO Fever > 38.3 ANC 500 or less Evaluation for at least 3 days
Neutropenic FUO Opportunistic bacterial infections Herpes Virus Aspergillosis Candidiasis
HIV FUO Fever > 38.3 Duration > 4 weeks (outpatient) or
> 3 days (inpatient) HIV infection confirmed
HIV FUO CMV MAC PCP Drug induced Kaposi’s Sarcoma Lymphoma
Infections Tuberculosis (especially extrapulmonary)
Abdominal abscessesPelvic abscessesDental abscessesEndocarditisOsteomyelitisSinusitisCytomegalovirusEpstein-Barr virusHuman immunodeficiency virusLyme diseaseProstatitisSinusitis
Infections As duration of fever increases,
infectious etiology decreases Malignancy and factitious fevers are
more common in patients with prolonged FUO.
Malignancies Chronic leukemia
LymphomaMetastatic cancersRenal cell carcinomaColon carcinomaHepatomaMyelodysplastic syndromesPancreatic carcinomaSarcomas
Autoimmune Adult Still's disease
Polymyalgia rheumaticaTemporal arteritisRheumatoid arthritisRheumatoid feverInflammatory bowel diseaseReiter's syndromeSystemic lupus erythematosusVasculitides
Miscellaneous Drug-induced fever
Complications from cirrhosisFactitious feverHepatitis (alcoholic, granulomatous, or lupoid)Deep venous thrombosisSarcoidosis
Diagnosis Failure to reach a diagnosis is not
uncommon 20% of cases remain undiagnosed Even if extensive investigation does
not identify a cause, these patient’s still have favorable outcomes.
Diagnosis Comprehensive History Physical Exam
Confirm fever and document pattern Laboratory Data
History Recent travel Exposure to pets and other animals Sexual history Work environment Contact with other people with similar
symptoms Family history Past medical history list of medications
Include OTC
Physical Exam Skin Mucus membranes Lymphadenopathy Organomegaly
Diagnosis A cost-effective individualized
approach is essential in the evaluation of these patients to prevent performing inappropriate tests.
Diagnosis of Fever of Unknown Origin
Diagnostic Testing CBC LFTs ESR Urinalysis Blood cultures Further testing should be based on
abnormalities in the initial workup
Diagnosis PPD testing is inexpensive screening
tool that should be used on all FUO patients that do not have a known positive reaction
Diagnosis If initial testing is inconclusive- more
specific testing should be performed based on clinical suspicion
Serologies CT Ultrasounds MRI Nuclear Medicine Scans
Chest radiograph Tuberculosis, malignancy, Pneumocystis carinii pneumonia
CT of abdomen or pelvis with contrast agent Abscess, malignancy
Gallium 67 scan Infection, malignancy
Indium-labeled leukocytes Occult septicemia
Technetium Tc 99m Acute infection and inflammation of bones and soft tissue
MRI of brain Malignancy, autoimmune conditions
PET scan Malignancy, inflammation
Transthoracic or transesophageal echocardiography Bacterial endocarditis
Venous Doppler study Venous thrombosis
Diagnosis More invasive testing, such as LP or biopsy of
bone marrow, liver, or lymph nodes, should be performed only when clinical suspicion shows that these tests are indicated or when the source of the fever remains unidentified after extensive evaluation.
When the definitive diagnosis remains elusive and the complexity of the case increases, an infectious disease, rheumatology, or oncology consultation may be helpful.