Fever of unknown origin pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: febris continua e causa ignota; febris e causa ignota; febris E.C.I.; FUO; PUO; pyrexia of unknown origin
Overview
The exact pathogenesis of [disease name] is not fully understood.
OR
It is thought that [disease name] is the result of / is mediated by / is produced by / is caused by either [hypothesis 1], [hypothesis 2], or [hypothesis 3].
OR
[Pathogen name] is usually transmitted via the [transmission route] route to the human host.
OR
Following transmission/ingestion, the [pathogen] uses the [entry site] to invade the [cell name] cell.
OR
[Disease or malignancy name] arises from [cell name]s, which are [cell type] cells that are normally involved in [function of cells].
OR
The progression to [disease name] usually involves the [molecular pathway].
OR
The pathophysiology of [disease/malignancy] depends on the histological subtype.
Pathophysiology
Classic FUO
Classic FUO 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.[2] 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 (health care-associated) FUO
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), immobilization (decubitus, thromboembolic event). Sinusitis in the intensive care unit is associated with nasogastric and orotracheal tubes.[1][2] 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]
Neutropenic (immune-deficient) FUO
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][2]
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][2]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Harrison's Principles of Internal Medicine 16th Edition, The McGraw-Hill Companies, ISBN 0-07-140235-7
- ↑ 2.0 2.1 2.2 2.3 The Oxford Textbook of Medicine Edited by David A. Warrell, Timothy M. Cox and John D. Firth with Edward J. Benz, Fourth Edition (2003), Oxford University Press, ISBN 0-19-262922-0