Pyrexia of Unknown Origin Quiz

Pyrexia of Unknown Origin (PUO)

• PUO is also known as pyrexia of undetermined etiology, meaning prolonged fever
• Normal body temperature is 37.0 ± 0.3°C
• Pyrexia is a body temperature higher than normal
• A PUO diagnosis requires
  • Illness lasting at least 3 weeks
  • Temperature above 38°C on several occasions
  • No established diagnosis after 1 week

Common Causes of PUO

• Tuberculosis is the most common infectious cause of PUO

  • Commonly affects developing countries and is prevalent in immigrant populations in developed countries.
  • Also seen in immunosuppressed patients

• Disseminated infections

  • Bacteria or tuberculosis (TB) can affect the liver, spleen, lymph nodes, bone, pericardium, meninges, or genitourinary system, but initial symptoms may not be obvious aside from fever
  • In some cases, lung field infections might not manifest for several weeks after pyrexia onset.
  • In elderly patients, the lungs might appear clear, tuberculin test might be negative, and a history of vague constitutional symptoms and progressive anemia could be possible indicators.

• Infective endocarditis

  • Must be considered in all PUO patients
  • Positive blood cultures are key to diagnosis, but bacteremia detection might sometimes be difficult due to prior antibiotics delaying bacterial growth, inadequate culture methods not detecting fastidious organisms like anaerobes or fungi, or infection with organisms like coxiella

• Localized abscesses

  • Intra-abdominal sites are most common
  • Abscesses in the liver or biliary tract might be asymptomatic in the early stages.
  • Pain or tenderness in the right hypochondrium could appear later, and alkaline phosphate levels might increase.
  • Other possible areas include the urinary tract, renal carbuncle, perinerphric abscess, and subphrenic sources.

Other Infectious Diseases

• Brucellosis
• Cytomegalovirus infection
• Meningococcemia
• Relapsing fever

Neoplasms

• Some neoplasms are associated with fever; it can be the only symptom in certain cases
  • Examples include lymphoma, hypernephromas, leukemia, hepatoma, and atrial myxoma
  • Lymphoma, especially when located in the retroperitoneal lymph nodes (in 5% of Hodgkin's disease cases), may be difficult to diagnose using blood lymphocyte markers along with bone marrow examination and abdominal CT scanning
  • Leukemia often presents with pyrexia, but in chronic forms, the cause is usually a secondary infection.
  • Hypernephromas might be occult, with 10% of patients initially presenting pyrexia. They often produce endogenous pyrogens, and may spread to the liver to cause fever, requiring liver biopsy.

Connective Tissue Diseases

• Patients with connective tissue and diseases may present with prolonged (low grade) fever, but very few other symptoms such as skin lesions or joint involvement.
  • This symptom presentation is seen in conditions such as juvenile rheumatoid arthritis, temporal arteritis, and systemic lupus erythematosus.

Drugs

• Almost any drug can cause pyrexia.
• Medications should be stopped during PUO investigations to check for potential side effects on fever.
• Cutaneous manifestations are associated with most drug fevers, but might be absent in cases caused by salicylates, phenytoin, methyldopa, isoniazid, or iodine.

Other Causes

• Sarcoidosis and other granulomas
• Inflammatory bowel disease (IBD)
• Pulmonary emboli
• Whipple's disease
• Familial Mediterranean fever (FMF)
• Kawasaki disease
• Hypothalamic lesions
• Thyroiditis
• Pheochromocytoma
• Hereditary urticaria, deafness, amyloid syndrome
• Factitious fever
• Psychogenic fever

Fever Patterns

• Types of fevers include intermittent, sustained or continuous, remittent, relapsing, monospike, double spike and multispike.

Diagnostic Approach to PUO

• Detailed patient history
• Full systematic clinical examination
• Routine tests
• Special hematological tests
• Special chemical and organ tests
• Radiological investigations
• Therapeutic tests
• Prolonged Observation
• Repeated examination and testing
• Exploratory laparotomy (if necessary)

Treatment of PUO

• Rationale for treatment
  • Avoid harm from potential secondary effects of fever such as tachycardia, febrile convulsions (children), hypercatabolic states, sweating and fluid losses, and encephalopathy
  • Achieve patient comfort following diagnosis.
• Timing of treatment
  • Do not treat fever if the patient can tolerate it during follow up and diagnosis testing.
• Treatment methods
  • Sponging the body with isopropranolol or water
  • Cooling blankets
  • Turkish massage for cooling
  • Immersion in a water bath or ice
  • Antipyretics (aspirin or acetaminophen)
  • Specific therapy for established cause or if a therapeutic test is suggestive.