Fever, undiagnosed after 1 week of routine study or 3 outpt visits or 3 days
in the hospital
(*REF: Arch IM 10-9-95;155:1989 De Kleijn E.M. - Netherlands)
Indium 111-labled polyclonal human IgG scintigraphy has the overall sensitivith
of 81% & specificity of 69%. The positive predictive value was 69% &
negative predictive value was 82%. It is helpful.
Fever of >101 F (38.3 C) occurs on several occasions in a hospitalized
pt, in whom infection was not present or incubating on admission. 3 days
of investigation, including at least 2 days' incubation of cultures is the
minimum duration for this dx.
Occult nosocomial infections (infected sinusitis in intubated pts, prosthetic
devices infection, acalculous cholecystitis, Clostridium difficile toxin
in the stool), infected IV lines, recurrent pulm. embolism, transfusion-related
viral infection, & drug fever are possible diagnoses .
Fever of >101 F (38.3 C) on several occasionis in a pt with <500
neutrophil/cc, with no diagnosis after 3 days of investigation, including
at least 2 days' incubation of cultures.
These pts are susceptible to bacterial & fungal bacteremic infections
& to infections involving catheters, including septic thrombophlebitis,
as well as to perianal infections. Candida & Aspergillus infections are
common. Viral infections due to herpes simplex or CMV are sometimes causes
of FUO in this group.
Fever of >101 F on several occasions over a period of >4 weeks for
outpts or >3 days' duration in the hospital pt with HIV infection, with
no diagnosis after 3 days of investigation, including at least 2 days' incubation
of cultures. Hiv infection alone may be a cause. Mycobacterium avium
intracellulare (MAI), toxoplasmosis, CMV, TB, Pneumocystis carinii,
salmonellosis, cryptococcosis, histoplasmosis, non-Hodgking's lymphoma, and
importantly, drug fever are all possible causes.
Differential Diagnosis of Diseases causing FUO
in adults in the U.S.
A. Infections (36% in 1952-57, 23%
in 1980-89) 1. Systemic infections
Mycoplasma infections: Tuberculosis, MAI, other atypical mycobacteria
D. Other specific causes (25% in
1952-57, 10% in 1970-80, 27% in 1980-89)
1. Granulomatous diseases: sarcoidosis, idiopathic granulomatous hepatitis,
starch peritonitis, & infectious granulomatous diseases as TB, brucellosis,
2. Inflammatory bowel disease
3. Drug fever
Antimicrobial: penicillins, cephalosporins,sulfonamides, B lactams,