Fever and PUO Flashcards
What investigations should be ordered for fever?
FBE, CRP, ESR
Renal function, Liver function
CXR
Urine and blood culture
Why is prolonged fever disadventageous?
Because fevers are highly metabolically demanding
Which hormone acts on the fever centre of the hypothalamus to increase the temperature set point?
PGE2
What are some signs that take longer to present in prolonged fever?
Cough, crepitations
Lymphenopathy/splenomegaly
Thyroid tenderness/temporal art. tenderness
Arthralgia, rash, arthritis
How does body temperature vary throughout the day?
Lowest in the morning
Highest in the afternoon
What will the body temperature of a person with rigors be?
Normal - rigors is a part of the process to increase temperature
What is the normal oral temperature range?
35.8-37.8
How does the body act to lose heat?
Sweat
Peripheral vasodilation
Reduce physical activity
Where in the brain is body temperature regulated?
In the posterior hypothalamus by heat sensing neurons
What are the leading causes of PUO
Connective tissue disorders ~30%
Malignancies ~30
Infections ~20%
Other ~10%
- Drug
- Factitious
- Benign pyrexia
What is classic cause of intra-abdominal abscesses?
Amoeba that has travelled by the bile duct
Why is LPS a more rapid stimulator of fever?
Because it acts directly on the fever centre
What is the cut off for fever?
>37.2 for morning oral temperature
>37.8 for oral temperature at any time
Who are some at risk patients?
Recent travellers
Asplenic
Neutropenia
IVDU
Diabetic
What is piloerection?
Hair standing up
What is required for subacute bacterial endocarditis to occur?
Valve abnormality
What abnormalities might you see in an FBE of someone with prolonged fever that might be diagnostic?
Neutrophilia left shift - greater proportion of newly produced neutrophils
Atypical lymphocytosis
Malaria
When should meningocaemia be considered as the cause of a fever?
Very rapid onset of severe fever and rigors
Accompanied rash
What infection should be considered in febrile patients with a history of contact with toddlers?
Cytomegalovirus infection
When should falciparum malaria be considered the cause of a fever presentation?
When the patient has a recent history (within a few months) of travel to an endemic zone
When should bacterial meningitis be considered as the cause of a presentation of fever?
When there is accompanied heahache and neck stiffness
What is the approach to take with some who has PUO?
Take a thorough history
- onset and duration
- localising symptoms
- severity
Is there really fever?
Consider risk factors
- country of origin/travel
- new sexual partners
- animal contact
- IVDU
- occupation
- past hx/ family hx/ new medications
When should a necrotising soft tissue infection be considered as the cause of a presentation of fever?
When this is accompanied localised severe pain
When should toxic shock symdrome be considered as the cause of a presentation of fever?
When there is accompanied sun burn like rash
What infection should be considered in febrile patients with a history of animal/farm contact?
Psittacosis - atypical pneumonia from birds
Q fever from farm animals
Why does fever occur?
Create the optimal temperature for certain enzymes to act at
What are rigors?
A feeling of intense cold
Uncontrollable shaking
Striking pallor of face and limbs
Piloerection
Leaves suffers exhausted
What are the criteria for pyrexia of unknown origin?
Illness for 2-3 weeks
Body temperature of 38.3 on several occasions
No diagnosis after intelligent investigations
