Pyrexia of unknown origin (PUO)

Question 1

What is the definition of fever?

Answer 1

• elevation of body temperature above normal (37C) - variation of up to 0.8C daily (circadian rhythm): low in early morning, high in early evening - Part of the systemic inflammatory response syndrome (SIRS)

Question 2

What is a pyrogen?

Answer 2

substances which cause fever

Question 3

What do we need to look for on NEWS charts?

Answer 3

Patterns between HR, temp and RR

Question 4

What is the definition of pyrexia of unknown origin?

Answer 4

• temp > 38.3C - recorded on multiple occasions - present for at least three weeks - defied diagnosis after one week of hospital evaluation

Question 5

What is nosocomial PUO?

Answer 5

develops in hospital, undiagnosed after 3 days

Question 6

What is neutropenic PUO?

Answer 6

undiagnosed fever in patient with neutrophils <500/mm3

Question 7

What is HIV-associated PUO?

Answer 7

Fever in a patient with HIV infection - present and undiagnosed for more than three days in an inpatient or four weeks in an outpatient

Question 8

What is important is gather during a history exploring PUO?

Answer 8

• Travel - occupation & hobbies – exposure to allergens - family history and age of onset - familial fevers e.g. tumor necrosis factor receptor-associated periodic syndrome - TRAPS - past medical and surgical history - drug history

Question 9

Examination

Answer 9

• including skin, eyes, oral cavity, nails and lymph nodes repeated examination often - worthwhile

Question 10

What are the initial investigations of PUO?

Answer 10

Simple things first: chest x-ray, urinalysis, full blood count, CRP

Question 11

Give a list of things that indicate more investigation and the investigations themselves.

Answer 11

New murmur: echocardiography (trans-oesophageal echo may be needed) Headaches: temporal artery biopsy Drug misuse: screen for blood-borne viruses

Question 12

When is imaging useful in PUO?

Answer 12

more valuable if they have some “direction” cannot always differentiate between infection and inflammation anatomical changes may not develop in immunocompromised hosts (e.g. neutropenic patients and abscesses)

Question 13

What are some invasive investigations for PUO?

Answer 13

obtain tissue for culture and histology bone marrow and liver often examined as part of blind investigation Malignancy, TB, lymphoma diagnostic laparotomy Rarely necessary

Question 14

What is the treatment of PUO?

Answer 14

therapeutic trial - this is rarely used Response of temporal arteritis to steroids is dramatic - usually within 48 hrs

Question 15

Please elaborate on fabricated fever.

Answer 15

fever is real but self-induced self injection common (self injection of jobbys)

Question 16

What is the prognosis of PUO?

Answer 16

Spontaneous resolution of PUO commoner in young compared with old patient

Question 17

What is the treatment of PUO without diagnosis?

Answer 17

Some patients with no diagnosis respond to NSAIDs or steroids (steroid responsive PUO)