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

A

RA
SLE

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
Q

What need to be careful with FUO in imunodeficiency

A

Blunted typical inflam response eg lacking symtpoms, ‘normal’ WCC when been low
Lack of radiological changes

26
Q

FUO in HIV

A

Seroconversion illness
AIDS -
PCP, Mycobacterial, toxoplasmosis, CMV, lymphoma

27
Q

Erythema nodosum ass

A

TB, strep, IBD, Recent anti-inflam drugs

28
Q

Infective endo signs

A

Janeway lesions, oslers nodes, splinter haemorrhages, petechiae eye

29
Q

Lab investigations for PUO

A

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
Q

Imaging for FUO

A

CXR
US liver/spleen
Cross section CT
HRCT
CT PET
Labelled white cell scan/scintigraphy (cancer monitoring)
Bone scan
MRI