Pyrexia of Unknown Origin Flashcards
What is the definition of pyrexia with unknown origin?
Fever - elevation of body temp above 38C, part of inflammatory response syndrome
Pyrogens - substances which cause fever, endogenous and exogenous which act on hypothalamus to cause reduction of heat loos
What is Petersdorf and Beeson?
Temp. above 38C
Recorded on multiple occasions and present for at least 3 weeks
Defied diagnosis after one week of hospital evaluation
What is the modern definition of pyrexia of unknown origin?
3 outpatient visits or 3 days in hospital or one week of outpatient investigation
What are the types of pyrexia of unknown origin (PUO)?
Classical PUO
Nosocomial PUO - develops in hospital and undiagnosed after 3 days
Neutropenic PUO - undiagnosed fever with neutrophils above 500
HIV-associated PUO - fever in patient with HIV - present for more than 3 days inpatient
What are the main causes of classical PUO?
Infections
Tumours
Inflammatory
Miscellaneous - ex. PE
Also undiagnosed
What are some causes of HIV related PUO?
Mycobacterium tuberculosis
Mycobacterium avium
Pneumocystis
Unknown
More than one causative agent
What is involved in the history and examination of PUO assessment?
History - travel, hobbies, FH, past medical and surgical history, drug history and pattern of fever
Exam - eyes, skin, oral, nails and lymph nodes
Repeated examinations
What is a feature of Still’s disease?
blanching rash which can be fliting
What are the initial investigations for pyrexia with unknown origin?
Chest X-ray, urinalysis, FBC, WCC, C-reactive protein and erythrocyte, blood cultures taken at times of fever, urea, creatinine, electrolytes and LFTs
What could be a further investigation for tropical travel?
Blood for malarial parasites, dengue, HIV, bone marrow for leishmaniasis
Less likely if more than 21 days after return
What could be used for further investigation of new heart murmur?
Echocardiogram
What investigation could be used for further investigation of micro. haematuria?
Auto-antibodies and possible renal biopsy
US
What further investigation can be done for TB contact?
Sputum smear, bone marrow and mantoux
What further investigation could be done for drug misuse?
Screen for blood borne viruses
Are imaging techniques good investigation for PUO?
More valuable if have some indication
Can’t differentiate between infection and inflammation
Anatomical changes may not develop in immunocompromised host
What imaging techniques can be used for PUO?
CT scan - ex. liver abscess
CT PET scan - ex. arteritis
US - ex. small vegetation on mitral valve
When are invasive investigation used for PUO?
Obtain tissue for culture and histology
Bone marrow and liver often examined as part of blind investigation - malignancy, TB and lymphoma
Diagnostic laparotomy - rare
What is the treatment for pyrexia of unknown origin?
Therapeutic trial - rare, suspected mycobacterial infection and vasculitis
Diagnosis of mycobacterium TB is unlikely if no response to chemo after 2 weeks
What is fabricated fever?
Fever is real but self induced, self injection common, microbiology usually strongest clue
Psychiatric expertise should be sought
What is the outcome of PUO?
Spontaneous resolution of PUO commoner in young patients
Some patient with no diagnosis respond to NSAIDs and steroids
Regular re-appraisal required
How many PUO patients remain undiagnosed?
1 in 4
