Pyrexia of Unknown Origin (PUO) Flashcards

1
Q

what is normal temperature?

A

37 centigrade is normal

Varies a lot between people and time of day

Lower in morning

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2
Q

Pyrexia of Unknown Origin - Definitions

what is a fever?

A

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)

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3
Q

Pyrexia of Unknown Origin - Definitions

What are pyrogens? and what types are there?

A

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

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4
Q

Raised __ and __ that goes along with the fever

A

RR

HR

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5
Q

what is the old (Petersdorf and Beeson (1961)) and modern definitions of pyrexia?

A

Petersdorf and Beeson (1961):

› temp > 38.3C

› recorded on multiple occasions

› present for at least three weeks

› defied diagnosis after one week of hospital evaluation

Modern definition is broader i.e. No diagnosis after:

› 3 outpatient visits or

› 3 days in hospital or

› One week of outpatient investigation

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6
Q

What are the different types of Pyrexia of Unknown Origin?

A

Classical PUO

Nosocomial PUO

Neutropenic PUO

HIV-associated PUO

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7
Q

what is Nosocomial PUO?

A

develops in hospital, undiagnosed after 3 days

Nosocomial in a hospitalised patient

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8
Q

what is Neutropenic PUO?

A

undiagnosed fever in patient with neutrophils <500/mm3

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9
Q

what is HIV-associated PUO?

A

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

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10
Q

what are the different causes of classical PUO?

A

Categorised in 4/5 main areas

Infections

Tumour disease

Inflammatory diseases

Other

No diagnosis

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11
Q

Pyrexia of Unknown Origin - assessment

what information should you gather in a history?

A

travel, occupation, hobbies, family history, past medical and surgical history, drug history, pattern of fever

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12
Q

Pyrexia of Unknown Origin - assessment

what should you examine?

A

including skin, eyes, oral cavity, nails and lymph nodes

repeated examination often worthwhile

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13
Q

what initial investigations would you do? (simple things first)

A

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) (ESR should be elevated)

Blood cultures taken at times of fevers

Urea, creatinine, electrolytes, liver function tests

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14
Q

Pyrexia of Unknown Origin - further investigation

what investigation would you do for an indication of Tropical travel?

A

Blood for malarial parasites, Dengue, HIV, bone marrow for leishmaniasis

Less likely if >21 days since return

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15
Q

Pyrexia of Unknown Origin - further investigation

what investigation would you do for an indication of a new murmur?

A

echocardiography (trans-oesophageal echo may be needed)

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16
Q

Pyrexia of Unknown Origin - further investigation

what investigation would you do for an indication of a headache?

A

temporal artery biopsy (TA)

17
Q

Pyrexia of Unknown Origin - further investigation

what investigation would you do for an indication of Micro. Haematuria?

A

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

18
Q

Pyrexia of Unknown Origin - further investigation

what investigation would you do for an indication of Tb contact?

A

sputum smear, bone marrow, Mantoux,

19
Q

Pyrexia of Unknown Origin - further investigation

what investigation would you do for an indication of durg misuse?

A

screen for blood-borne viruses

20
Q

:Imaging techniques

› more valuable if they have some “_______”

› cannot always differentiate between _______ and ____________

› anatomical changes may not develop in ________________ hosts (e.g. neutropenic patients and abscesses)

(white cell scan shown below)

A

direction

infection and inflammation

immunocompromised

21
Q

what is shown here?

A

Liver abscess

22
Q

What technique is shown here?

A

CT PET scan for PUO

Positron Emission tomography

Fluorodeoxyglucose marker (FDG)

taken up greater in cells that are inflammed

23
Q

what invasive procedures can be carried out?

A

obtain tissue for culture and histology

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

diagnostic laparotomy - Rarely necessary

24
Q

what is the treatment?

A

žTherapeutic trial

  • Rarely used
  • suspected Mycobacterial infection (anti-tuberculous therapy)
  • suspected vasculitis or conn. tissue disorder
    (steroids)

žDiagnosis of Mtb unlikely if no response to chemotherapy within two weeks

žResponse of temporal arteritis to steroids is dramatic - usually within 48 hrs

25
Q

how is fabricated fever caused, its diagnosis and its effects?

A

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

26
Q

what is the outcome of pyrexia of unkowning origin?

A

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 months

27
Q

Summary:

Most PUOs are not due to ______

Careful and _______ history and examination is crucial

Imaging is most valuable if it has some “_______” i.e. don’t just do ______ scans

Therapeutic trials are a ____ ______!

About 1 in 4 patients remain ________

A

infection

repeated

direction

random

last resort

undiagnosed