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2A - Infection > Pyrexia of Unknown Origin > Flashcards

Pyrexia of Unknown Origin Flashcards

1
Q

What is a fever?

A

Elevation of body temperature above normal (37oC)

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2
Q

What is the variation of normal body temperature?

A

Normal body temperature has variation up to 0.8oC daily, being low in early morning and high in early evening

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3
Q

Fever is a normal part of what?

A

Systemic inflammatory response syndrome (SIRS)

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4
Q

What does SIRS stand for?

A

Systemic inflammatory response syndrome

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5
Q

What is a pyrogen?

A

Substances that cause fever

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6
Q

What are examples of pyrogens?

A
  • Endogenous
    • Cytokines
  • Exogenous
    • Endotoxins from G-ve bacteria
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7
Q

What do pyrogens act on?

A

Hypothalamic thermoregulatory centre to cause reduced heat loss and hence fever

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8
Q

What does PUO stand for?

A

Pyrexia of unknown origin

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9
Q

What is pyrexia of unknown origin?

A

Pyrexia with no diagnosis after:

  • 3 outpatient visits or
  • 3 days in hospital or
  • One week of outpatient investigation
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10
Q

What are the different classes of PUO?

A
  • Classical PUO
  • Nosocomial PUO
    • Develops in hospital, undiagnosed after 3 days
  • Neutropenic PUO
    • Undiagnosed fever in patient with neutrophils <500/mm3
  • HIV associated PUO
    • Fever in patient with HIV present and undiagnosed for more than 3 days in an inpatient or 4 weeks as outpatient
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11
Q

What is nosocomial PUO?

A
  • Develops in hospital, undiagnosed after 3 days
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12
Q

What is neutropenic PUO?

A
  • Undiagnosed fever in patient with neutrophils <500/mm3
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13
Q

What is HIV associated PUO?

A
  • Fever in patient with HIV present and undiagnosed for more than 3 days in an inpatient or 4 weeks as outpatient
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14
Q

What are some causes of classical PUO?

A
  • Infection
  • Malignancy
  • Collagen (inflammatory)
  • Other
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15
Q

What are the most common causes of HIV associated PUO?

A
  1. Mycobacterium tuberculosis - causes TB
  2. Mycobacterium ovium - causes TB
  3. Unknown
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16
Q

What parts of the history are important for assessment for PUO?

A
  • Travel, occupation, hobbies, family history, past medical and surgical history, drug history, pattern of fever
17
Q

What part of the examination are important for assessment for PUO?

A
  • Skin, eyes, oral cavity, nails and lymph nodes
18
Q

What are the initial investigations for PUO?

A
  • 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
19
Q

What are some further investigations for PUO?

20
Q

What is a limitation of imaging for PUO?

A
  • Cannot always differentiate between infection and inflammation
  • Anatomical changes may not be present in immunocompromised hosts
21
Q

What imaging may be done for PUO?

A
  • USS
  • CT
  • MRI
  • Radio-labelled white cell scan
  • Isotope bone scan
22
Q

What invasive investigations may be done for PUO?

A
  • Obtain tissue for culture and histology (biopsy)
  • Bone marrow and liver often examined as part of blind investigation
    • Malignancy, TB, lymphoma
23
Q

What is the treatment of PUO?

A

Therapeutic trial:

  • Rarely used, but used if
    • Suspected mycobacterial infection (anti-tuberculosis therapy)
    • Suspected vasculitis or connective tissue disorder (steroids)
24
Q

What is a fabricated fever?

A

Fever is real but self-induced:

  • Microbiology may be strongest clue
  • Psychiatric expertise should be sought
25
Q

Describe the outcome of PUO?

A

Spontaneous resolution of PUO more common in young people

Some patients respond to NSAIDs or steroids

Regular re-appraisal required

26
Q

what are some classical causes of PUO that is more common now than in the past?

A

inflammatory (22%)

infection (16%)

malignancy (7%)

no diagnosis (51%)

27
Q

give an example of a pattern of familial fever that is specific to PUO

A

familial medeterrian fever

  • patients get bouts of high fever, muscle and joint pain which will resolve after a few days
28
Q

why is repeated examination for PUO important?

A
  • patients could develop a new murmur
  • some findings can be quite fleeting
29
Q

what can splinter haemorrhages indicate?

A

Endocarditis - infection of the heart valves

vasculits

chronic kidney disease

30
Q

give an example of some fleeting examination findings adn what this could indicate

A

rashes can be fleeting

  • blanching rash that comes and goes and is non specific
  • hughly suggestive of adult stools disease

2A - Infection (15 decks)

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