Pyrexia of Unknown Origin Flashcards
Define fever
Elevation of body temperature above normal (37C)
NB: there is a variation of up to 0.8C daily (circadian rhythm)
Define pyrogens
Substances which cause fever (can be endogenous or exogenous)
Define classical pyrexia of unknown origin (PUO)
A temperature of >38.3C recorded on multiple occasions and present for at least 3 weeks, where there is no diagnosis after 3 outpatient visits or 3 days in hospital
What are the 4 types of pyrexia of unknown origin?
- Classical
- Nosocomial
- Neutropenic
- HIV-associated
Define nosocomial PUO
Pyrexia which develops in hospital and remains undiagnosed after 3 days
Define neutropenic PUO
Undiagnosed fever in a patient with neutrophils <500/mm3
Define 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 particular aspects of the history are important in a suspected PUO? (6)
- Travel
- Occupation and hobbies
- Family history and age of onset - familial fevers (TRAPS)
- Past medical and surgical history
- Drug history
- Pattern of fever
Name some initial investigations useful in a PUO (6)
- Chest X-ray
- Urinalysis and urine microscopy
- Full blood count and differential white cell count
- C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
- Blood cultures taken at times of fevers
- Urea, creatinine, electrolytes, liver function tests
What indications would prompt you to consider further, more specific investigations of a PUO? (6)
- Tropical travel (malaria)
- New murmur (endocarditis)
- Headaches (temporal arteritis)
- Micro-haematuria (renal)
- TB contact
- Drug misuse (blood borne viruses)
What are the indications for trying out therapeutic trials in patients with PUO? (2)
- Suspected mycobacterial infection (anti-TB therapy)
- Suspected vasculitis or connective tissue disorder (steroids)
Define fabricated fever
Self-induced pyrexia
