🤒“Pyrexia of Unknown Origin: When Persistent Fever Challenges Clinical thinking”

General
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:face_with_thermometer:One of the most difficult situations in clinical practice is a patient who has had a fever for longer than three weeks, is not responding to antibiotics, has consistently negative cultures, and has inconclusive tests. Pyrexia of Unknown Origin (PUO), which is more of a test of clinical reasoning than a diagnosis, is defined by this circumstance. A persistent fever of ≥38.3°C that lasts longer than three weeks and for which no cause is found despite appropriate and systematic evaluation is known as PUO.

Infections, cancers, non-infectious inflammatory diseases, and miscellaneous causes are the four main groups of causes of PUO :

•Infections like deep-seated abscesses, infective endocarditis, and tuberculosis are still prevalent.

• Malignancies, especially leukemias and lymphomas, should be taken into account when fever is accompanied by lymphadenopathy, anemia, or weight loss.

•Vasculitis, adult-onset Still’s disease, and connective tissue diseases are examples of autoimmune and inflammatory conditions that frequently manifest subtly and call for a high degree of suspicion.

•The miscellaneous group includes endocrine disorders, thromboembolic disease, and drug fever, all of which are often disregarded.

:scientist:Smart Approach:

Instead of using reflexive treatment, PUO requires structure and patience.

✓Physical examinations and repeated history taking frequently uncover hints that were initially overlooked.

✓Unless the patient is unstable, empirical antibiotic escalation should be avoided as it may mask diagnostic results.

✓Instead of being ordered arbitrarily, laboratory markers of inflammation, targeted serological tests, and imaging should be directed by clinical indicators.

✓FDG PET-CT has become a useful tool in challenging cases to guide biopsies and identify occult infection, cancer, or inflammatory activity.

PUO
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:stethoscope:Conclusion:

In the end, PUO reminds medical professionals that fever is a symptom rather than an illness. Understanding the underlying mechanism causing the temperature is more important for management than trying to lower it. Thoughtful clinical reasoning frequently succeeds when routine investigations fail. PUO is one of the most humble yet instructive medical experiences because it rewards those who take their time, reflect, and think beyond the obvious.

“In PUO, time and thoughtful reasoning often succeed where urgency fails.”

:speech_balloon:Have you encountered a PUO case that challenged your clinical thinking?

MBH/AB

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PUO is the ultimate test of a clinician’s discipline: it requires moving from ‘treating the symptom’ to 'finding the source

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PUO is often not given due attention. In busy OP schedules, doctors often treat them by giving antipyretics and patients hesistate to return to doctor when the fever persists.

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PUO is less about chasing tests and more about disciplined clinical reasoning where patience, pattern recognition, and thoughtful investigation matter more than aggressive treatment.

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Overcoming PUO is about combining careful detective work, multidisciplinary careful work and ofcourse patient care.

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The most important step , but the one that unfortunately is rushed through in crowded OPDs is a thorough and comprehensive history of the patient. When done right it allows us to narrow down the diagnostics and reach our definitive diagnosis. PUO can be better diagnosed in the same way.