Pyrexia of Unknown Origin Flashcards
What is a normal temperature?
37C
Fever
Elevation of body temperature above normal 37C
What response is fever part of?
The systemic inflammatory response (SIRS)
How does temperature vary throughout the day?
Variation of up to 0.8C daily (circadian rhythm)
- Low in the early morning
- High in the early evening
Pyogenes
Substances which cause fever
- Endogenous e.g. cytokine
- Exogenous e.g. endotoxins from gram negative bacteria
How do pygogenes cause fever?
They act at the hypothalamic thermoregulatory centre to cause reduced heat loss and hence fever
How is pyrexia of unknown origin defined?
Fever with no diagnosis after:
- 3 outpatient visits or
- 3 days in hospital or
- 1 week of outpatient investigation
Nosocomial PUO
Pyrexia which develops in hospital and is undiagnosed after 3 days
Neutropenic PUO
Undiagnosed fever in a patient with neutrophils <500mm^3
HIV associated PUO
Fever in a patient with HIV infection which is present and undiagnosed for more than 3 days in an inpatient stay or 4 weeks as an outpatient
Causes of classical PUO
- Infection
- Malignancy
- Inflammatory
- No diagnosis
What bacteria are commonly involved in HIV related PUO?
- Mycobacterium tuberculosis
- Mycobacterium ovium
- Unknown
- More than 1 causative agent
What history should be taken in PUO?
- Travel
- Occupation
- Hobbies
- Family history
- Past medical and surgical history
- Drug history
- Pattern of fever
What examination should be carried out when assessing PUO?
Repeated examination is often worthwhile
- Skin
- Eyes
- Oral cavity
- Lymph nodes
What initial investigations should be carried out for PUO?
- Chest X-Ray
- Urinalysis and urine microscopy
- Full blood count and differential white cell count
- C-Reactive Protein and Erythrocyte Sedimentation Rate
- Blood cultures taken at times of fevers
- Urea, creatinine, electrolytes, liver function tests