Fever of unknown origin resident survival guide

Fever of unknown origin Resident Survival Guide
Diagnostic Criteria
Classification
Causes
Complete Diagnostic Approach
Empiric Therapy
Dos
Don'ts

Main article: Fever of unknown origin

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Synonyms and keywords: febris continua e causa ignota; febris e causa ignota; febris E.C.I.; FUO; PUO; pyrexia of unknown origin

Diagnostic Criteria

In 1961, Petersdorf and Beeson suggested the following criteria:

• Fever higher than 38.3°C (100.9°F) on several occasions
• Persisting without diagnosis for at least 3 weeks
• At least 1 week's investigation in hospital

Classification

In 1991, Durack and Street proposed a revised definition in which cases of FUO are categorized into four subclasses: classic FUO, nosocomial (health care-associated) FUO, neutropenic (immune-deficient) FUO, and HIV-related FUO.

Classic FUO

Fever (>38.3° C or >100.9° F) for >3 weeks with no identified cause after 3 days of hospital evaluation or ≥3 outpatient visits

Nosocomial (health care-associated) FUO

Fever (>38.3° C or >100.9° F) in hospitalized patients receiving acute care and with no infection present or incubating on admission if the diagnosis remains uncertain after 3 days of appropriate evaluation

Neutropenic (immune-deficient) FUO

Fever (>38.3° C or >100.9° F) in patients with immunodeficiencies if the diagnosis remains uncertain after 3 days of appropriate evaluation, including negative cultures after 48 hours

HIV-related FUO

Fever (>38.3° C or >100.9° F) for >3 weeks in outpatients with confirmed HIV infection or >3 days in inpatients with confirmed HIV infection if the diagnosis remains uncertain after appropriate evaluation

Causes

Major causes of fever of unknown origin are as follows:

• Infections

Localized

– Endocarditis

– Intra-abdominal infections

– Urinary tract infections

– Osteomyelitis

– Upper respiratory tract infections

– Infected peripheral vessels

Generalized

– Bacterial

– Mycobacterial

– Fungal

– Viral

– Parasitic

• Neoplasia

– Lymphoproliferative disorders

– Leukemia

– Myelodysplastic syndrome

– Solid tumors

• Rheumatic disorders

– Adult onset Still's disease

– Giant cell arteritis

– Polymyalgia rheumatica

– Other forms of vasculitis (e.g., polyarteritis nodosa, Wegener's granulomatosis, Takayasu's arteritis)

– Other rheumatologic disorders (e.g., systemic lupus erythematosus, rheumatoid arthritis, Sjogren's syndrome)

• Endocrine disorders

– Hyperthyroidism

– Thyroiditis

– Adrenocortical insufficiency

• Hereditary disorders (e.g., familial Mediterranean fever)
• Factitious fever
• Miscellaneous

– Granulomatous disorders

– Hepatitis

– Vascular disorders (e.g., pulmonary embolism, hematoma)

– Drug fever

Complete Diagnostic Approach

Abbreviations: CBC, complete blood count; CI, cardiac index; CK-MB, creatine kinase MB isoform; CVP, central venous pressure; DC, differential count; ICU, intensive care unit; INR, international normalized ratio; LFT, liver function test; MAP, mean arterial pressure; PCWP, pulmonary capillary wedge pressure; PT, prothrombin time; PTT, partial prothrombin time; SaO2, arterial oxygen saturation; SBP, systolic blood pressure; ScvO2, central venous oxygen saturation; SvO2, mixed venous oxygen saturation; SMA-7, sequential multiple analysis-7.

Suspected FUO

Empiric Antibiotic Therapy

Dos

Don'ts

References