Fever and pyrexia of unknown origin Flashcards

1
Q

Where is body temp controlled

A

Sensors and receptors in hypothalamus

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2
Q

Temp reducing responses

A

Vasodilation
Sweating
Increased ventilation

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3
Q

Temp raisinging repsonses (mechainisms of effervescence)

A

Vasoconstriction
Shivering
Piloerection
Increased metabolism

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4
Q

Hyperthemia vs fever

A

Bodies mechanisms to cool not sufficient enugh to cool body temperature, so whole body temp rises = hyperthermia
Fever = prostaglandin E1 acts on thermostatic set point regardless of external environemnt
eg hyperhtermia = external conditions, fever = internal.

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5
Q

Why do we ger fever

A

Make ourselves hotter - not ideal for bacteria but ideal for immune system functioning

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6
Q

Pyrogenic factors - infectious

A

microbes and microbial prodcts eg
Gram - bacteria - LPS/Endotoxin
G+ - exotoxins, peptioglycans
Viruses
Other microorganisms

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7
Q

Non infectious pyrogenic factors

A

antigen-antibody complexes
Compleetn
Non infectious inflammation - genesis irritatnts
Drugs - antibiotics, steroids, chemotheray agents

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8
Q

Cytokines that are pyrogenic (fever inducing)

A

TNF
IL-1, 6
IFN

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9
Q

Where are endogenous pyrogens derived from

A

Cells in boody - cytokines released by
Mononuclear, macrophages, T-lymphocytes, kupffer cells, endothelial cells, tumour cells

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10
Q

Classical fever patterns

A

Sustained - constant above basal temp, half degree variation
Intermittent - temp returns to normal, swings of fever in cycles less than 24 hours
Remittent - significant rapid variation, baseline does not return to normal (rises)
Relapsing - period of any pattern fever -> afebrile -> returning fever >24 hr cycle

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11
Q

What is intermittent fever classically ass with

A

Abscesses eg empyemas

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12
Q

What causing relapsing fever

A

Malaria etc
48-72 hr cycles of fever relapsing

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13
Q

What is defined as pyrexia of unknown origin

A

Sustained or recurrent pyrexias >3 weeks
No identified cause after evaluation in hospital for 3 dyas or >3 outpatient visits

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14
Q

Types of pyrexia of unknown origin

A

Classic
Nosocomial
Immunodeficient
HIV

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15
Q

Common causes of classic fever of unexplained origin

A

1/4 - undiagnosed
20% - miscellaneous
20% - Connective tissue disorders
1/4 - infection
15% - neoplasms eg malignant

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16
Q

What happens to causes of FUO >60 yrs

A

Causes are different -Infections <10%
CTD >30%
Malignancy much more important

17
Q

Infectious causes of FUO

A

Abscess
Infective endocarditis
TB
Complicated UTI
Travel - melioidosis, visceral leishmaniasis, amoebic abcess

18
Q

Connective tissue auses of FUO in young

A

Stills disease
JRA

19
Q

Adult CTD causes of FUO

20
Q

Elderly CTD causes of FUO

A

Giant cell arteritis
Polymyalgia Rheumatica

21
Q

When is an FUO nosocomial

A

> 48 hrs hospitalised
No infection present or incubating at admission
Diagnosis uncertain >3 days appropriate evaluation
Microbiologucal cultures incubated for >2 days

22
Q

Causes of nosocomial FUO

A

Catheters/devices
Thrombophlebitis
UTI/RTI
Drug fevers
C.diff treatment (broad spec ABs)
ICU - ventialtors, ET tubes, NG tubes
Stroke

23
Q

FUO imunodeficiency causes

A

Cell-mediated imunodeficiency - congenital, biologic/immunomodulatory therapies
Neutropenia - haematological, chemotherapy

24
Q

Definition of neutropenia

A

<500 neurtophils/ul

25
What need to be careful with FUO in imunodeficiency
Blunted typical inflam response eg lacking symtpoms, 'normal' WCC when been low Lack of radiological changes
26
FUO in HIV
Seroconversion illness AIDS - PCP, Mycobacterial, toxoplasmosis, CMV, lymphoma
27
Erythema nodosum ass
TB, strep, IBD, Recent anti-inflam drugs
28
Infective endo signs
Janeway lesions, oslers nodes, splinter haemorrhages, petechiae eye
29
Lab investigations for PUO
Blood cultures Blood borne viruses - HIV.HBV/HCV Blood films - cells, parasites Serology FBC U+E/LFT/Bone chemistry TFTs Inflam markers - CRP, ESR, ALP Autoantibodies - ANA, dsDNA Stool, urine samples Ascitic/pleural/synovial fluid Bone marrow Biopsy
30
Imaging for FUO
CXR US liver/spleen Cross section CT HRCT CT PET Labelled white cell scan/scintigraphy (cancer monitoring) Bone scan MRI