Fever of unknown origin
You don't need to be Editor-In-Chief to add or edit content to WikiDoc. You can begin to add to or edit text on this WikiDoc page by clicking on the edit button at the top of this page. Next enter or edit the information that you would like to appear here. Once you are done editing, scroll down and click the Save page button at the bottom of the page.
| Fever of Unknown Origin Classification and external resources | |
| ICD-10 | R50. |
|---|---|
| ICD-9 | 780.6 |
| MedlinePlus | 003090 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-525-6884
Please Take Over This Page and Apply to be Editor-In-Chief for this topic: There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us [2] to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.
Fever of unknown origin (FUO), pyrexia of unknown origin (PUO) or febris e causa ignota (febris E.C.I.) refers to a condition in which the patient has an elevated temperature but despite investigations by a physician no explanation has been found.[1][1][1][1][1]
If the cause is found it usually is a diagnosis of exclusion, that is, by eliminating all possibilities until only one explanation remains, and taking this as the correct one.
Definition
In 1961 Petersdorf and Beeson suggested the following criteria:[1][1]
- Fever higher than 38.3°C (101°F) on several occasions
- Persisting without diagnosis for at least 3 weeks
- At least 1 week's investigation in hospital
Presently FUO cases are codified in four subclasses.
Classic FUO
This refers to the original classification by Petersdorf and Beeson. The outpatient setting has been included to reflect current medical practise. The current definition requires three outpatient visits or three days in hospital or 1 week of "intelligent and invasive" ambulatory investigation.[1] Studies show there are five categories of conditions: infections (i.e. abscesses, endocarditis, tuberculosis, and complicated urinary tract infections), neoplasms (i.e. lymphomas, leukaemias), connective tissue diseases (i.e. temporal arteritis and polymyalgia rheumatica, Still's disease, systemic lupus erythematosus, and rheumatoid arthritis), miscellaneous disorders (i.e. alcoholic hepatitis, granulomatous conditions), and undiagnosed conditions.[1][1]
The new definition is broader, stipulating three outpatient visits or 3 days in the hospital without elucidation of a cause or 1 week of "intelligent and invasive" ambulatory investigation.
Nosocomial
Nosocomial FUO refers to pyrexia in patients that have been admitted to hospital for at least 24 hours. This is commonly related to hospital associated factors such as, surgery, use of urinary catheter, intravascular devices (i.e. "drip", pulmonary artery catheter), drugs (antibiotics induced Clostridium difficile colitis, and drug fever), immobilisation (decubitus, thromboembolic event). Sinusitis in the intensive care unit is associated with nasogastric and orotracheal tubes.[1][1][1] Other conditions that should be considered are deep-vein thrombophlebitis, and pulmonary embolism, transfusion reactions, acalculous cholecystitis, thyroiditis, alcohol/drug withdrawal, adrenal insufficiency, pancreatitis.[1]
Immune-deficient
Immunodeficiency can be seen in patients receiving chemotherapy or in hematologic malignant neoplasms. Fever is concommittent with neutropenia (neutrophil <500/uL) or impaired cell-mediated immunity. The lack of immune response masks a potentially dangerous course. Infection is the most common cause.[1][1][1]
Human immunodeficiency virus (HIV)-associated
- Further information: Human immunodeficiency virus
HIV-infected patients are a subgroup of the immunodeficient FUO, and frequently have fever. The primary phase shows fever since it has a mononucleosis-like illness. In advanced stages of infection fever mostly is the result of a superimposed illness.[1][1][1]
Some important causes
Extrapulmonary tuberculosis is the most frequent cause of FUO.[1] Drug fever, as sole symptom of an adverse reaction to medication, should always be thought of. Disseminated granulomatoses such as Tuberculosis, Histoplasmosis, Coccidioidomycosis, Blastomycosis and Sarcoidosis are associated with FUO. Lymphomas are the most common cause of FUO in adults. Thromboembolic disease (i.e. pulmonary embolism, deep venous thrombosis) occasionally shows fever. Although infrequent, its potentially lethal consequences warrant evaluation of this cause. Endocarditis, although uncommon, is another important thing to consider. An underestimated reason is factitious fever. Patients frequently are women that work, or have worked, in the medical field and have complex medical histories.[1]
Diagnosis
A comprehensive and meticulous history (i.e. illness of family members, recent visit to the tropics, medication), repeated physical examination (i.e. skin rash, eschar, lymphadenopathy, heart murmur) and a myriad of laboratory tests (serological, blood culture, immunological) are the cornerstone of finding the cause.[1][1]
Other investigations may be needed. Ultrasound may show cholelithiasis, echocardiography may be needed in suspected endocarditis and a CT-scan may show infection or malignancy of internal organs. Another technique is Gallium-67 scanning which seems to visualize chronic infections more effectively. Invasive techniques (biopsy and laparotomy for pathological and bacteriological examination) may be required before a definite diagnosis is possible.[1][1]
[Positron Emission Tomography] using radioactively labelled Fluorodeoxyglucose (FDG) has been reported to have a sensitivity of 84% and a specificity of 86% for localizing the source of fever of unknown origin.[1]
Despite all this, diagnosis may only be suggested by the therapy chosen. When a patient recovers after discontinuing medication it likely was drug fever, when antibiotics or antimycotics work it probably was infection. Empirical therapeutic trials should be used in those patients in which other techniques have failed.[1]
Therapy
Unless the patient is acutely ill, no therapy should be started before the cause has been found. This is because non-specific therapy rarely is effective and mostly delays diagnosis. An exception is made for neutropenic patients in which delay could lead to serious complications. After blood cultures are taken this condition is aggressively treated with broad-spectrum antibiotics. Antibiotics are adjusted according to the results of the cultures taken.[1][1][1]
HIV-infected persons with pyrexia and hypoxia, will be started on medication for possible Pneumocystis jirovecii infection. Therapy is adjusted after a diagnosis is made.[1]
Prognosis
Since there is a wide range of conditions associated with FUO, prognosis depends on the particular cause.[1] If after 6 to 12 months no diagnosis is found, the chances diminish of ever finding a specific cause.[1] However, under those circumstances prognosis is good.[1]
References
External links
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
