Pyrexia of Unknown Origin (PUO) Flashcards
what is normal temperature?
37 centigrade is normal
Varies a lot between people and time of day
Lower in morning
Pyrexia of Unknown Origin - Definitions
what is a fever?
elevation of body temperature above normal (37C)
variation of up to 0.8C daily (circadian rhythm):
low in early morning, high in early evening
Part of the systemic inflammatory response syndrome (SIRS)
Pyrexia of Unknown Origin - Definitions
What are pyrogens? and what types are there?
substances which cause fever
endogenous e.g. cytokines
exogenous e.g. endotoxins from G-ve bacteria
act at hypothalamic thermoregulatory centre to cause reduced heat loss and hence fever
Raised __ and __ that goes along with the fever
RR
HR
what is the old (Petersdorf and Beeson (1961)) and modern definitions of pyrexia?
Petersdorf and Beeson (1961):
› temp > 38.3C
› recorded on multiple occasions
› present for at least three weeks
› defied diagnosis after one week of hospital evaluation
Modern definition is broader i.e. No diagnosis after:
› 3 outpatient visits or
› 3 days in hospital or
› One week of outpatient investigation
What are the different types of Pyrexia of Unknown Origin?
Classical PUO
Nosocomial PUO
Neutropenic PUO
HIV-associated PUO
what is Nosocomial PUO?
develops in hospital, undiagnosed after 3 days
Nosocomial in a hospitalised patient
what is Neutropenic PUO?
undiagnosed fever in patient with neutrophils <500/mm3
what is HIV-associated PUO?
fever in a patient with HIV infection - present and undiagnosed for more than three days in an inpatient or four weeks in an outpatient
what are the different causes of classical PUO?
Categorised in 4/5 main areas
Infections
Tumour disease
Inflammatory diseases
Other
No diagnosis
Pyrexia of Unknown Origin - assessment
what information should you gather in a history?
travel, occupation, hobbies, family history, past medical and surgical history, drug history, pattern of fever
Pyrexia of Unknown Origin - assessment
what should you examine?
including skin, eyes, oral cavity, nails and lymph nodes
repeated examination often worthwhile
what initial investigations would you do? (simple things first)
Chest X-Ray
Urinalysis and urine microscopy
Full blood count and differential white cell count
C-Reactive Protein and Erythrocyte Sedimentation Rate (acute phase reactants) (ESR should be elevated)
Blood cultures taken at times of fevers
Urea, creatinine, electrolytes, liver function tests
Pyrexia of Unknown Origin - further investigation
what investigation would you do for an indication of Tropical travel?
Blood for malarial parasites, Dengue, HIV, bone marrow for leishmaniasis
Less likely if >21 days since return
Pyrexia of Unknown Origin - further investigation
what investigation would you do for an indication of a new murmur?
echocardiography (trans-oesophageal echo may be needed)