Pyrexia of unknown origin Flashcards
what is normal body temperature
~37C
variation of up to 0.8C daily, low in early morning, high in early evening
define fever
elevation of body temp above normal
part of the systemic inflammatory response (SIRS)
define pyrogens
substances which cause fever
act at hypothalamic thermoregulatory centre to cause reduced heat loss and therefore fever
examples of pyrogens
endogenous e.g. cytokines
exogenous e.g. endotoxins from gram -ve bacteria
define pyrexia of unknown origin
temp >38C
recorded on multiple occasions
3 outpatient visits or 3 days in hospital or 1wk of outpatient investigation
define nosocomial PUO
develops in hospital
undiagnosed after 3 days
define neutropenic PUO
undiagnosed fever in patient w/ neutrophils <500/mm^3
define HIV associated PUO
fever in patient w/ HIV infection
present and undiagnosed for >3 days as an inpatient or >4wks in outpatient setting
causes of PUO
infections - becoming a less common cause malignancy inflammatory misc/other undiagnosed
causes of HIV related PUO
HIV itself mycobacterium infections tumours and lymphomas multiple causative diseases other
hx of PUO
travel occupation hobbies FHx PMH and surgical hx drug hx pattern of fever
examination of PUO
be thorough
skin, eyes, oral cavity, nails and lymph nodes
repeated examination often worthwhile
initial investigations
simple things first CXR urine analysis and microscopy FBC and differential WCC CRP and ESR (acute phase reactants) blood cultures taken at times of fevers - take at least 3 sets of blood cultures urea, creatinine, electrolytes, LFTs
further investigations - tropical travel
blood for malarial parasites, dengue, HIV, bone marrow for leishmaniasis
less likely if >21 days since return
further investigations - new murmur
echo (trans-oesophageal echo may be needed)
