pyrexia of unknown origin Flashcards
what is normal temp
~37
fever temp
> 38
pyrogens
substances which cause fever
endogenous e.g. cytokines
exogenous e.g. endotoxins from gram -ive bacteria
PUO modern definitino
no diagnosis after 3 outpatient visits, 3 days in hospital or one week of outpatient investigation
different types of PUO
classical PUO nosocomial PUO (develops in hosp, 3 days no diagnsis inc 2 day blood cultutes) neuropenic PUO (neutrophils <500) HIV-associated PUO
causes of classical PUO
infection
neoplasms
inflammation
causes of HIV related PUO
tumours
mycobacterial infections
fabricated fever
fever is real but self-induced
self injection common
need psychiatric inervention
managing PUO
some patients with no diagnosis respond to NSAIDs or steroids
spontaneous resolution PUO commoner in young (<35yrs) than elderly
how do pyrogens cause fever
elevate set point of hypothalamic regulatory centre
- vasoconstriction
- decreased peripheral heat loss
- fever
petersdorf and Beeson definition PUO
> 38.3 multiple occasions for 3+ weeks
1wk hospital evaluation
if no diagnosis and they are unwell what to do
consider trial anti-TB therapy or steroids
fever of tetrian
(quartan malaria)
fever every 3/4 days
Ix if travel to tropical areas
blood films for malarial parasites
serology for travel related infections
Ix if new/changing heart murmur
ECHO
