Pyrexia of unknown origin

Question 1

Definition of fever

Answer 1

elevated body temp more than 37 degrees Celsius or higher than normal

Question 2

What does body temperature naturally vary with and therefore when is body temp highest and lowest?

Answer 2

0.8 degrees variation with the circadian rhythm

low early morning and high early evening

Question 3

What are pyrogens?

Answer 3

substances which cause fever

Question 4

Endogenous pyrogens example

Answer 4

cytokines

Question 5

Exogenous pyrogens example

Answer 5

endotoxins from gram negative bacteria

Question 6

How do pyrogens cause fever?

Answer 6

act as hypothalamic thermoregulatory centre to cause reduced heat loss

Question 7

Modern definition of pyrexia of unknown origin

Answer 7

No diagnosis after 3 outpatient visits or 3 days in hospital or 1 week of outpatient investigations

Question 8

4 types of PUO

Answer 8

classical
nosocomial
neutropenic
HIV associated

Question 9

Causes of HIV related PUO

Answer 9

mycobacterium tuberculosis or avium

unknown or more than 1 cause

Question 10

Causes of classical PUO

Answer 10

collagen disease
infection
neoplasm etc

Question 11

Infection causes of classical PUO

Answer 11

TB, HIV, Endocarditis

Question 12

Malignancy causes of classical PUO

Answer 12

lymphoma, mets or renal

Question 13

Inflammatory causes of classical PUO

Answer 13

temporal arteritis
IBD
SLE
vasculitis

Question 14

Other causes of classical PUO

Answer 14

drug fevers
venous thrombosis
sarcoidosis

Question 15

Questions in history of PUO

Answer 15

travel, occupation, hobbies, PMH, drugs, allergens, FH and age of onset

Question 16

Examination of patient with PUO

Answer 16

skin, eyes, oral cavity, nails, LN

often worthwhile repeating

Question 17

Initial investigations of PUO

Answer 17

CXR 
FBC
urinalysis and urine microscopy 
CRP and ESR 
blood cultures, taken at time of fever 
urea, creatinine, electrolytes, LFT

Question 18

Some further investigations you may undertake

Answer 18

malarial parasites 
HIV test 
temporal artery biopsy 
echo 
bone marrow

Question 19

In who may anatomical changes not develop in to be seen by imaging?

Answer 19

immunocompromised

Question 20

Examples of invasive investigations

Answer 20

bone marrow and liver aspirate

diagnostic laparotomy rare

Question 21

Treating PUO

Answer 21

TB drugs? - therapeutic trials

steroids

Question 22

What is fabricated fever?

Answer 22

fever which is real but self induced

Question 23

Common cause of fabricated fever?

Answer 23

self injection

Question 24

Biggest clue in fabricated fever

Answer 24

microbiology - eg multiple different organisms on blood cultures at different times

Question 25

Outcome of PUO

Answer 25

Spontaneous resolution often in younger
respond to NSAIDS or steroids
re appraisal often needed