Fever of unknown origin
| Fever of unknown origin | |
|---|---|
| Other names | Pyrexia of unknown origin, febris e causa ignota |
| Duration | ≥3 weeks |
| Types | Various |
| Causes | Infections, malignancies, non-infectious inflammatory diseases, others |
| Diagnostic method | Clinician-verified temperature at or above 38.3 Celsius at any measurement site on several occasions over at least 3 weeks. |
| Differential diagnosis | Factitious fever, malingering |
| Frequency | 2–3 % of all medical admissions |
Fever of unknown origin (FUO) refers to a condition in which the patient has an elevated temperature (fever) for which no cause can be found despite investigations by one or more qualified physicians. If the cause is found, it is usually a diagnosis of exclusion, eliminating all possibilities until only the correct explanation remains.
In the West, the classical medical definition of the FUO required a clinician-verified measurement of temperature of ≥38.3 at any site on several (varied) occasions over 3 weeks, though in the recent years the threshold of ≥38.0 has been becoming increasingly more prevalent.