Pyrexia of Unknown Origin Flashcards
What body temperature is considered a fever?
Anything above 38 degrees celsius
What are pyrogens?
Substances causing fever
Can be indogenous or exogenous
What is the definition of pyrexia of unknown origin?
Pyrexia with no diagnosis after 3 outpatient visits or 3 days in hospital or a week of outpatient investigation
What is nosocomial PUO?
Develops in hospital and is undiagnosed after three days
What is neutropenic PUO?
Undiagnosed fever in patient with neutrophils <500mm3
What is HIV-associated PUO?
Fever in a patient with HIV infection present and undiagnosed for more than three days as an inpatient or four weeks as an outpatient
How is PUO assessed?
Careful history and examination. History should involve asking about travel, occupation, hobbies, family history, past medical and surgical history, drug history and pattern of fever. Examination should involve checking skin, oral cavity, nails and lymph nodes. Repeat examination is often useful.
What initial investigations can be helpful in 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 (usually three, taken at times when fever is present)
- Urea, creatinine, electrolytes and liver function tests
What imaging modalities can be useful in PUO?
X-ray
CT scan
PET scan
What invasive procedures can be useful in PUO?
Taking tissue for culture and histology
Bone marrow examination
Liver examination
Diagnostic laparotomy (rarely necessary).
What is a fabricated fever?
Fabricated fevers can cause PUO, in which the fever is real but it is self-induced. Normal microbiology may be the biggest clue
Referral to psychiatry can help
What are the possible outcomes of PUO?
- Spontaneous resolution of PUO (commoner in young population compared to older)
- Some patients without no diagnosis respond to NSAIDs or steroids
