Prexia of unknown origin Flashcards
what is the definition of a fever?
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)
what are pyrogens?
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
what is the modern definition of pyrexia?
3 outpatient visits or
3 days in hospital or
One week of outpatient investigation
what is nonsocomial PUO?
develops in hospital, undiagnosed after 3 days
what is neutropenic PUO?
undiagnosed fever in patient with neutrophils <500/mm3
what is HIV associated PUO?
fever in a patient with HIV infection - present and undiagnosed for more than three days in an inpatient or four weeks in an outpatient.
how do you assess a patient with PUO?
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
what initial investigations are done for PUO?
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
what further investigations are done for tropical travel?
Blood for malarial parasites,Dengue, HIV, bone marrow for leishmaniasis
Less likely if >21 days since return
what further investigations are done for new murmur?
echocardiography (trans-oesophageal echo may be needed)
what further investigations are done for Headaches?
temporal artery biopsy (TA)
what further investigations are done for Micro. Haematuria?
Auto-antibodies +/- renal biopsy, (polyarteritis) ultrasound (renal Ca)
what further investigations are done for TB contact?
sputum smear, bone marrow, Mantoux,
what further investigations are done for drug misuse?
screen for blood-borne viruses
what imaging techniques are offered for PUO?
CT/PET scan
Trans oesophageal echogram
what are invasive investigations for PUO?
obtain tissue for culture
and histology
bone marrow and liver
often examined as part
of blind investigation
Malignancy, TB, lymphoma
diagnostic laparotomy
Rarely necessary
what is treatment for PUO?
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
what is fabricated fever?
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
what is the outcome of PUO?
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
