Pyrexia of unknown cause Flashcards
Define a fever?
Body temp above 37degrees
What body response is a fever apart of?
Systemic inflammatory response syndrome
What is a pyrogen?
Substance which causes a fever
types of endogenous pyrogens?
cytokines
types of exogenous pyrogens?
endotoxins from gram-ve bacteria
how do pyrogens cause a fever?
act at hypothalmic thermoregulatory centre to cause reduced heat loss
Petersdorf and Beeson definition of pyrexia of unknown cause
temp >38.8degrees,
recorded on multiple occasions,
present for at least 3 weeks,
defied diagnosis after 1 week of hospital evaluation
Modern definition of pyrexia of unknown cause?
3 outpatients visits or,
3 days in hopsital or
one week of outpatient investigation
Name the 4 types of pyrexia of unknown origin? (PUO)
classical,
nosocomial,
neutropenic,
HIV-associated
Define nosocomial PUO?
develops in hospital,
undiagnosed after 3 days
Define neutropenic PUO?
undiagnosed fever in patient with neutrophils <500/mm3
Define HIV-associated PUO
fever in a patient with HIV,
present for >3days inpatient or 4 weeks outpatient
Most common causes of classical PUO?
infection,
malignancy,
inflammation
Most common causes of HIV-associated PUO
mycobacterium tuberculosis,
mycobacterium avium
Initial investigations of PUO?
CXR,
urinalysis and urine microscopy,
FBC and differential wcc,
C-reactive protein and erythrocyte sedimentation rate,
Blood culture,
urea, creatinine, electrolytes, liver function tests
