Prexia of unknown origin

Question 1

what is the definition of a fever?

Answer 1

elevation of body temperature above normal (37C)
variation of up to 0.8C daily (circadian rhythm):
low in early morning, high in early evening
Part of the systemic inflammatory response syndrome (SIRS)

Question 2

what are pyrogens?

Answer 2

substances which cause fever

endogenous e.g. cytokines
exogenous e.g. endotoxins from G-ve bacteria
act at hypothalamic thermoregulatory centre to cause reduced heat loss and hence fever

Question 3

what is the modern definition of pyrexia?

Answer 3

3 outpatient visits or
3 days in hospital or
One week of outpatient investigation

Question 4

what is nonsocomial PUO?

Answer 4

develops in hospital, undiagnosed after 3 days

Question 5

what is neutropenic PUO?

Answer 5

undiagnosed fever in patient with neutrophils <500/mm3

Question 6

what is HIV associated PUO?

Answer 6

fever in a patient with HIV infection - present and undiagnosed for more than three days in an inpatient or four weeks in an outpatient.

Question 7

how do you assess a patient with PUO?

Answer 7

History – take your time
travel, occupation, hobbies, family history, past medical and surgical history, drug history, pattern of fever

Examination – be thorough
including skin, eyes, oral cavity, nails and lymph nodes
repeated examination often worthwhile

Question 8

what initial investigations are done for PUO?

Answer 8

Initial investigations

• simple things first
  Chest X-Ray
  Urinalysis and urine microscopy
  Full blood count and differential white cell count
  C-Reactive Protein and Erythrocyte Sedimentation Rate (acute phase reactants)
  Blood cultures taken at times of fevers
  Urea, creatinine, electrolytes, liver function tests

Question 9

what further investigations are done for tropical travel?

Answer 9

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

Question 10

what further investigations are done for new murmur?

Answer 10

echocardiography (trans-oesophageal echo may be needed)

Question 11

what further investigations are done for Headaches?

Answer 11

temporal artery biopsy (TA)

Question 12

what further investigations are done for Micro. Haematuria?

Answer 12

Auto-antibodies +/- renal biopsy, (polyarteritis) ultrasound (renal Ca)

Question 13

what further investigations are done for TB contact?

Answer 13

sputum smear, bone marrow, Mantoux,

Question 14

what further investigations are done for drug misuse?

Answer 14

screen for blood-borne viruses

Question 15

what imaging techniques are offered for PUO?

Answer 15

CT/PET scan
Trans oesophageal echogram

Question 16

what are invasive investigations for PUO?

Answer 16

obtain tissue for culture
and histology

bone marrow and liver
often examined as part
of blind investigation
Malignancy, TB, lymphoma

diagnostic laparotomy
Rarely necessary

Question 17

what is treatment for PUO?

Answer 17

Therapeutic trial
Rarely used
suspected Mycobacterial infection (anti-tuberculous therapy)
suspected vasculitis or conn. tissue disorder
(steroids)
Diagnosis of Mtb unlikely if no response to chemotherapy within two weeks
Response of temporal arteritis to steroids is dramatic - usually within 48 hrs

Question 18

what is fabricated fever?

Answer 18

fever is real but self-induced
self injection common
microbiology may be strongest clue
patient often continues despite being very sick
psychiatric expertise should be sought rather than direct confrontation

Question 19

what is the outcome of PUO?

Answer 19

Spontaneous resolution of PUO commoner in young compared with old patient

Some patients with no diagnosis respond to NSAIDs or steroids (steroid responsive PUO)

Regular re-appraisal required
The answer may not become apparent for many