Pyrexia of Unknown Origin

Question 1

What is the definition of a PUO?

Answer 1

Fever >38.3 on several occasions

Persisting >3 weeks without diagnosis despite >1 week of intensive investigations

Question 2

What is a classical PUO?

Answer 2

Standard PUO including >3 nights in hospital or >3 outpatient visits with ambulatory investigations

Question 3

Give 4 causes for a classical PUO

Answer 3

1) Infections (incl: abscesses, endocarditis, TB, complicated UTIs)
2) Neoplasms
3) Connective tissue diseases
4) Undiagnosed conditions

Question 4

What is a healthcare-associated PUO?

Answer 4

PUO following >24 hours in hospital (for something else)

Question 5

Give 5 causes for a healthcare-associated PUO

Answer 5

1) Surgery
2) Drugs eg vancomycin, penicillins, serotonergics
3) Medical devices eg catheter, IV line bacteraemia
4) Infections eg LRTI (incl ventilator-associated in ITU), C. diff colitis
5) Immobilisation

Question 6

What is a neutropaenic PUO?

Answer 6

PUO concomitant with neutropaenia (less than 500/uL) and subsequent lack of cellular response. MEDICAL EMERGENCY!!

Question 7

Give 5 causes for a neutropaenic PUO

Answer 7

1) Chemotherapy
2) Haematological malignancies
3) Infections that require neutrophils eg fungal (aspergillus)/bacterial sepsis, mycobacteria
4) Graft v Host Disease
5) Drug fever

Question 8

What is HIV PUO?

Answer 8

Recurrent PUO in a patient with HIV

Question 9

Give 5 causes for HIV PUO

Answer 9

1) Seroconversion
2) Infection eg: TB, bacterial, disseminated MAI, PCP, CMV, Cryptococcus, Toxoplasmosis, Histoplasmosis
3) Kaposi’s sarcoma
4) Lymphoma
5) Drug fever

Question 10

Which sort of infections are likely to be responsible for a healthcare-associated PUO? (4)

Answer 10

Ventilator-associated LRTI
IV line bacteraemia
C. diff colitis
Catheter associated UTI

Question 11

Which infections are likely to be responsible for a neutropaenic PUO? (3)

Answer 11

Fungal (aspergillus) sepsis
Bacterial sepsis
Mycobacteria

Question 12

Which infections are likely to be responsible for HIV PUO? (7)

Answer 12

TB
Disseminated MAI
PCP
CMV
Cryptococcus
Toxoplasmosis
Histoplasmosis

Question 13

In PUO when should therapy commence?

Answer 13

• If possible, not until diagnosis has been reached.

- Always after taking samples for culture unless pt is unstable

Question 14

Name 3 types of test that shouldn’t be forgotten when investigating a PUO

Answer 14

• Vasculitis screen: pANCA, cANCA, Rho, La (Rheum review if arthritis)
• Bence Jones/protein electrophoresis (myeloma etc)
• Dip urine/casts?

Question 15

Which 3 familial diseases should be considered as causes for PUO?

Answer 15

Familial Mediterranean fever (FMF)
Fabry’s disease
Cyclic neutropaenia