Pyrexia Of Unknown Origin

Question 1

What is PUO?

Answer 1

Pyrexia of unknown origin is when there is no diagnosis for after 3 outpatient visits or 3 days in hospital or 1 week of outpatient investigations

Classifications: classical, nosocomial (develops in hospital), neutropenia (neutrophils <500), HIV associated

Question 2

What are the major disease categories which can present with PUO?

Answer 2

Classical: infection, neoplasm, inflammatory

HIV associated: mycobacterium tuberculosis, mycobacterium avium

Question 3

What is the approach to the PUO patient?

Answer 3

History - good
Examination - thorough
Investigate - urinalysis + microscopy, CXR, FBC, WCC, CRP, ESR, blood cultures, u+e, creatinine, LFTs
Further investigation depends on history and indication eg travel, headaches, drugs
May do invasive investigations eg tissue samples, bone marrow

Question 4

What imaging is available for use in investigation of PUO?

Answer 4

Valuable if have direction

• CT scan
• CTPET
• USS

Question 5

What is the place of the therapeutic trial in PUO patients?

Answer 5

Rarely used (last resort), more for suspected mycobacterium infection, suspected vasculitis or connective tissue disorder

Usually spontaneous resolution in the young, may respond to steroids or NSAIDs