PUO stands for Pyrexia of Unknown Origin.
Understanding Pyrexia of Unknown Origin (PUO)
Pyrexia of Unknown Origin, commonly abbreviated as PUO, refers to a prolonged fever for which a clear cause cannot be readily identified despite thorough medical evaluation. It is a diagnostic challenge in medicine, requiring a systematic approach to uncover the underlying condition.
Clinical Definition of PUO
For a fever to be classified as Pyrexia of Unknown Origin, specific criteria must be met, highlighting the persistence and diagnostic difficulty associated with the condition:
- Temperature Threshold: The individual must experience a temperature greater than 38.3℃ (101°F) on several occasions.
- Duration of Illness: The illness, characterized by fever, must persist for more than three weeks.
- Diagnostic Challenge: There must be a failure to reach a definitive diagnosis after one week of initial hospital investigation or intensive outpatient evaluation.
Why PUO is a Diagnostic Challenge
The broad range of potential causes for PUO makes it complex to diagnose. These can include:
- Infections: Persistent or unusual infections that are difficult to detect, such as tuberculosis, endocarditis, or hidden abscesses.
- Malignancies: Certain cancers, particularly lymphomas, leukemias, and renal cell carcinoma, can present with fever as a primary symptom.
- Autoimmune Diseases: Connective tissue diseases like systemic lupus erythematosus (SLE), rheumatoid arthritis, and vasculitis often cause prolonged fevers.
- Miscellaneous Causes: Drug-induced fever, factitious fever (self-induced), and even some neurological disorders.
- Undiagnosed: In a significant percentage of cases, despite extensive investigation, the cause of the fever may remain unknown.
Approach to Investigating PUO
Investigating PUO typically involves a comprehensive series of diagnostic tests and consultations, often including:
- Detailed patient history and physical examination.
- Extensive blood tests (e.g., complete blood count, inflammatory markers, blood cultures).
- Imaging studies (e.g., chest X-ray, CT scans, MRI).
- Microbiological cultures and serological tests.
- Referrals to specialists, such as infectious disease experts, rheumatologists, or oncologists.
For more information on Pyrexia of Unknown Origin, you can consult reputable health resources such as Metro North Health.
