4. Pyrexia of unknown origins

Question 1

What is normal temeprature

Answer 1

37C

Question 2

What is a fever?

Answer 2

An elevation of body temperature above normal (37C)
Variation of up to 0.8C daily (circadian rhythm)
Part of the systemic inflammatory response syndrome (SIRS)

Question 3

What are Pyrogens?

Answer 3

Substances which cause fever
Endogenous e.g. cytokines
Exogenous e.g. endotoxins from G-ve bacteria
Act at hypothalmic thermoregulatory centre to cause reduced heat loss and hence fever

Question 4

What is meant by pyrexia of unknown origin?

Answer 4

No diagnosis after 3 outpatient visits or 3 days in hospital

Question 5

What is nosocomial PUO

Answer 5

Develops in hospital, undiagnosed after 3 days

Question 6

What is Neutropenic PuO

Answer 6

Undiagnosed fever in patietn with neutrophils under 500mm

Question 7

What is HIV associated PUO

Answer 7

present and undiagnosed fro more than= three days in an inpatient or four weeks in an outpatient

Question 8

What causes HIV infected patients to get unknown pyrexia

Answer 8

Mycobacterium tuberculosis

Mycobacterium avium

Question 9

`What inital investigations should you do for pyrexia of unknown origin?

Answer 9

CXR
Urinalysis
FBC and differential white cell counts
CRP and Erythrocyte sedimation rate (acute phase reactants)
Blood cultures taken at time of fevers
Urea,creatinine, electrolytes, LFT's

Question 10

What you would you do if someone has gone tropical travelling

Answer 10

Blood for malarial parasites, Dengue, HIV, bone marrow for leishmaniasis. less likely if >21 days since return

Question 11

What would you do if someone had a new-murmur

Answer 11

Echocardiography trans-oesophageal echo may be needed)

Question 12

What would you do if someone has Headaches?

Answer 12

temporal artery biopsy

Question 13

What would you do if someone has micro heamaturia?

Answer 13

Auto-antibodies, renal biopsy (polyarteritis)

ulatrasond (renal carcinoma)

Question 14

What would you do if there was Tb contact

Answer 14

Sputum smear, bone marrow, mantoux

Question 15

What would you do if someone is misusing drugs?

Answer 15

Screen for blood borne viruses

Question 16

What are the benefits/risks of using images to look at pyrexia of unknown origin

Answer 16

More valuable if they have direction
Cannot always differentiate between infection and inflammation
Anatomical changes may not develop in immunocomprimised hosts

Question 17

What tests should you do when you’re not sure what the cause is?

Answer 17

Obtain tissue for culture and histology
Bone marrow and liver often examined as part of a blind examination (malignancy, TB)
Diagnostic laparotomy

Question 18

What else can you do if you’re not sure what the cause is?

Answer 18

Trials is rarely used
Trial steroids for suspected vasculitis or connective tisue disorder
Respond of temporal arteritis to steroids is dramatic usually within 48 hours
Antituberculosis therapy can be used if you suspect mycobacterial infection. Diagnosis unlikely if no response within two weeks

Question 19

What is the outcome of pyrexia of unknown origin?

Answer 19

spontaneous resolution commoner in young compared with old patient
Some patients with no diagnosis respond to NSAIDS or steroids
regular repraisal may be required