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Which condition is the most common infection causing pyrexia of unknown origin?
Which condition is the most common infection causing pyrexia of unknown origin?
What is the minimum duration of fever required to classify a condition as pyrexia of unknown origin?
What is the minimum duration of fever required to classify a condition as pyrexia of unknown origin?
Which of the following patient populations is most likely to show tuberculosis as a cause of pyrexia of unknown origin?
Which of the following patient populations is most likely to show tuberculosis as a cause of pyrexia of unknown origin?
What percentage of patients with pyrexia of unknown origin are likely to have infections as a cause?
What percentage of patients with pyrexia of unknown origin are likely to have infections as a cause?
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Which of the following factors does NOT influence the likelihood of undiagnosed fever causes?
Which of the following factors does NOT influence the likelihood of undiagnosed fever causes?
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Which type of neoplasm is most commonly associated with pyrexia of unknown origin (PUO)?
Which type of neoplasm is most commonly associated with pyrexia of unknown origin (PUO)?
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In the diagnosis of hyperuephromas, what is the most useful diagnostic procedure?
In the diagnosis of hyperuephromas, what is the most useful diagnostic procedure?
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Which connective tissue disease is particularly known for causing prolonged low-grade fever with minimal additional manifestations?
Which connective tissue disease is particularly known for causing prolonged low-grade fever with minimal additional manifestations?
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Which of the following statements about drug-induced fever is true?
Which of the following statements about drug-induced fever is true?
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What characterizes intermittent fever as described in the classification of fever patterns?
What characterizes intermittent fever as described in the classification of fever patterns?
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What is the primary goal of treating pyrexia of unknown origin (PUO)?
What is the primary goal of treating pyrexia of unknown origin (PUO)?
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Which of the following conditions can rarely cause pyrexia of unknown origin (PUO)?
Which of the following conditions can rarely cause pyrexia of unknown origin (PUO)?
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Which diagnostic method is essential in the clinical investigation of pyrexia of unknown origin?
Which diagnostic method is essential in the clinical investigation of pyrexia of unknown origin?
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What can be a common diagnostic method for identifying infective endocarditis?
What can be a common diagnostic method for identifying infective endocarditis?
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Which condition is least likely to be misdiagnosed if a patient presents with a new systolic murmur?
Which condition is least likely to be misdiagnosed if a patient presents with a new systolic murmur?
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What may complicate the diagnosis of bacteraemia in a patient receiving antibiotics?
What may complicate the diagnosis of bacteraemia in a patient receiving antibiotics?
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What type of abscess is most commonly associated with pyrexia of unknown origin (PUO)?
What type of abscess is most commonly associated with pyrexia of unknown origin (PUO)?
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Which of the following is a known neoplasm that may present only with fever?
Which of the following is a known neoplasm that may present only with fever?
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Infections that may lead to PUO include all of the following except:
Infections that may lead to PUO include all of the following except:
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Which of these is considered a potential cause of localized abscesses in the body?
Which of these is considered a potential cause of localized abscesses in the body?
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What is a notable characteristic of acute osteomyelitis in the absence of significant clues?
What is a notable characteristic of acute osteomyelitis in the absence of significant clues?
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Study Notes
Pyrexia of Unknown Origin (PUO)
- PUO is defined as fever of unknown origin.
- PUO is also called pyrexia of undetermined etiology.
- A simple definition for prolonged fever.
- Normal body temperature is 37 ± 0.3°C .
- Pyrexia is a body temperature higher than normal.
Definitions
- Criteria for PUO include:
- Illness lasting at least 3 weeks.
- Temperature exceeding 38°C on several occasions.
- No diagnosis established after a 1-week hospital stay.
Retrospective Studies
- Most patients with PUO have common illnesses, not uncommon or rare conditions.
- Common conditions include:
- Infections (33%).
- Malignancies (20%).
- Connective tissue diseases (20%).
- Miscellaneous problems (remainder).
- In children, infectious illnesses are slightly more common than neoplastic diseases.
Common Causes
- Tuberculosis is the most common infection causing PUO.
- It's more common in developing countries, Asian immigrants in developed countries, and patients taking immunosuppressive drugs.
- Disseminated diseases (TB in organs like the liver, spleen, lymph nodes, bone, pericardium, or meninges) can present with no other obvious symptoms other than fever until weeks after the onset of the fever.
- This can also occur in lung-related infections but these areas may be clear of infection.
- Older patients may not show lung involvement; rather they may show vague constitutional symptoms and progressive anaemia.
- Liver and bone marrow are commonly involved. Histological and culture examinations are often diagnostic.
Infective Endocarditis
- Suspect in all PUO patients.
- Positive blood cultures confirm diagnosis, but bacteremia may be difficult to detect for a few reasons.
- Potential issues include previous antibiotic use, poor culture methods, difficult-to-detect organisms (anaerobes or fungi).
- Infections with organisms like Coxiella may also lead to undiagnosed PUO.
- Right-sided or mural endocarditis can present without a murmur.
Localized Abscesses
- Common PUO cause, often intra-abdominal.
- Possible dental or brain abscesses are less common.
- Abscesses may initially be hidden.
- Pain, tenderness in the right upper quadrant, and rising alkaline phosphatase values may appear later.
Other Potential Causes
- Travel history suggests possibility of amoebiasis, which may surface years later from illness.
- Previous surgery may also play a role as infection can surface later.
- Pelvic/paracolic pus and pancreatic abscesses may occur after pancreatitis..
- Other sites of cryptic infection include the urinary tract, with possibilities of renal carbuncle or perinerphric abscess (and possible no presence of pyuria or bacteriuria).
- Bone infection may arise without obvious associated characteristics.
Other Infections
- Brucellosis.
- Cytomegalovirus infection.
- Meningococcemia.
- Relapsing fever.
Neoplasms
- Some neoplasms are associated with fever; in some cases, fever may be the only presenting symptom. - Examples:
- Lymphoma.
- Hypernephroma.
- Leukemia.
- Hepatoma.
- Atrial myxoma.
- Lymphomas may be difficult to detect when they are contained in the retroperitoneal lymph nodes.
Leukemia
- May cause fever, more common in secondary infections of chronic forms.
Hypernephromas
- The 10% of patients with PUO may have these tumors; they often are hidden.
- Tumours can produce endogenous pyrogens; especially when liver is involved.
- A liver biopsy may be helpful.
Connective Tissue Diseases
- Patients with connective tissue diseases may have prolonged, low-grade fever with few accompanying symptoms such as skin lesions or joint issues.
- Examples: juvenile rheumatoid arthritis, temporal arteritis, and systemic lupus.
Drugs
- Almost any drug can cause fever.
- Discontinue meds during investigation phase, to observe potential effects.
- Cutaneous manifestations are common with drug-induced fevers but not always present.
- Possible culprits include salicylates, phenytoin, methyldopa, isoniazid, or iodine.
Other Causes
- Sarcoidosis/other granulomas.
- Inflammatory bowel disease (IBD).
- Pulmonary embolism.
- Whipple's disease.
- Familial Mediterranean fever (FMF).
Rare Diseases
- FMF.
- Kawasaki's disease.
- Hypothalamic lesions.
- Thyroiditis.
- Pheochromocytoma.
- Hereditary urticaria, deafness, amyloid syndrome (not all uncommon).
- Factitious fever and psychologically induced fever.
Fever Patterns
- Intermittent fever.
- Sustained (continuous) fever.
- Remittent fever
- Relapsing fever.
- Monospike fever.
- Double spike fever.
- Multispike fever.
Diagnostic Clinical Approach to PUO
- Detailed history.
- Full physical examination.
- Routine tests.
- Special hematological tests.
- Special chemical and organ tests.
- Radiological investigations.
- Biopsy (if needed).
Diagnostic Clinical Approach to PUO (continued)
- Therapeutic tests.
- Prolonged observation.
- Repeated examination and testing.
- Exploratory laparotomy (sometimes).
Treatment for PUO
- Why: Avoid harmful secondary effects (tachycardia, febrile convulsions in children, hypercatabolism, fluid loss, and encephalopathy). Provide patient comfort.
- When: Don't treat if patient tolerates fever during follow-up and diagnosis isn't evident yet.
-
How:
- Physical cooling methods like sponging with water or isopropanol, or cooling blankets.
- Turkish massage method or immersion in water/ice.
- Antipyretics like aspirin or acetaminophen.
- Specific therapy for the identified cause.
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Description
Explore the key concepts surrounding Pyrexia of Unknown Origin (PUO), including its definitions, criteria for diagnosis, and common causes. This quiz highlights the characteristics of PUO, emphasizing the importance of identifying underlying conditions that may lead to prolonged fever.
