Pyrexia of Unknown Origin

Question 1

What is are definitions of fever and pyrogens?

Answer 1

• elevation of body temp. above normal (37°C)
• substances which cause fever
• endogenous (e.g. cytokines)
• exogenous (e.g. endotoxins)
• act at hypothalamic thermoregulatory centre cause reduced heat loss -> fever

Question 2

What are the different types of PUO?

Answer 2

• classical PUO
• nosocomial PUO
• develops in hospital, undiagnosed after 3 days
• neutropenic PUO
• undiagnosed fever in patients withneutrophils < 500/mm³
• HIV-associated PUO
• fever in a patient with HIV

Question 3

What are the investigations for pyrexia of unkown origin?

Answer 3

• CXR
• urinalysis + urine microscopy
• FBC + differential WBC
• CRP + ESR
• blood cultures
• urea, creatinine, electrolytes, LFTs
• invasive
• tissue culture + histolology
• bone marrow + liver
• diagnostic laparotomy