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A. Fever without localizing symptoms, rash or lymphadenopathy
ii. Those with fever beyond 3 weeks (FUO)
Definition: Fever of unknown origin (FUO) is a term applied
to a febrile illness with temperatures exceeding >101?F (38.3?C) that
is at least 3 weeks' duration and remains undiagnosed after 3 days in
the hospital or after 3 outpatient visits. This is further categorized
1. Neutropenic (neutrophils </= 500):
check for perianal, periodontal infections and candidemia, aspergillosis.
HIV associated: mycobacterium avium,
non-Hodgkin's lymphoma, drug fever and
3. Nosocomial FUO: septic thrombophlebitis,
clostridium difficile colitis and drug fever.
4. Classic FUO:
inflammatory diseases and drug fever.
a. Infections: account for 1/3 of
Abscesses account for 1/3 of the causes. Most of these
are intra-abdominal as abscesses, abscesses elsewhere are easily diagnosed.
EBV in the young.
Lower urinary tract infections.
infective endocarditis, mycotic
aneurysms, infected atherosclerotic plaques.
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Malignancy: accounts for 1/3 of
the causes. Leukemia and
hypernephroma releases endogenous pyrogens.
and liver metastasis can also present with fever. Atrial myxoma.
c. Collagen vascular diseases: account
for 10%. SLE is an uncommon cause as it is readily diagnosed serologically.
d. Granulomatous disease without defined
familial Mediterranean fever, hypertriglyceridemia, drug related and
recurrent pulmonary embolism.
1. Thermometer in the tea cup routine.
2. Self-injection with pyrogenic containing substances.
3. Injection of medication known by the patient to