PYREXIA OF UNKNOWN OR (UNDTERMIND) ORIGIN (PUO)

ORFEVER OF UNKNOWN ORIGIN

(FUO)

Definition  

• A PUO has been defined as an intermittent temperature of at least 39 °C for over three weeks with at least a week’s worth of attempts to find the cause.

• When the usual investigations yield no answer, yet the fever persists, a tentative diagnosis of PUO is made until the cause can be identified

PUO : Causes• Infection is not the only type of disease

causing fever

Causes of PUO• Infections 45-55of cases• Malignancies 12-20% of

cases• Connective tissue disorders 10-15% of

cases• Hypersensitivity disorders• Rare metabolic conditions

• Tuberculosis (usually non-pulmonary)• Sepsis (hidden abscesses – liver, brain)• Infective endocarditis• Enteric fever• Brucellosis• Q-fever• Leptospirosis-relapsing fever• Infectious mononucleosis• Toxoplasmosis• Tropical diseases in temperate climates/latitudes – malaria,

dengue fever, yellow fever, etc. • Systemic fungal infections

• Over 140 separate diseases are listed in Harrison’s Principles of Internal Medicine.

PUO : Infectious Causes

Risk Factors

The following factors increase your chance of developing a PUO.

• Foreign travel, especially to developing and tropical countries

• Current medications (Drug reactions, Antibiotics, Epilepsy medications, Immune gobulin, Antipsychotics, Antihistamines)

• Cancer or brain tumor• Collagen vascular disease (an

autoimmune disorder of connective tissue) • HIV/AIDS• Current or recent hospitalization • Similar problems in the family

Diagnosis  

Many different tests may be indicated at some point in evaluating a PUO. Tests may include the following:

• Exhaustive studies of blood, urine, and all other bodily products

• Exhaustive imaging studies: x-rays, CT and MRI scans, ultrasound examinations

• Nuclear medicine studies • Endoscopies (lungs, stomach and intestines,

sinuses, etc.) • Biopsies of suspect tissues