Fever of unknown origin

General or Other | Emergency Medicine | Fever of unknown origin (Disease)


Fever of unknown origin refers to a condition in which the patient has an elevated temperature but despite investigations by a physician no explanation has been found.

Causes and Risk factors

While no initial cause is found for the fever most end up being the result of infections, cancers or an autoimmune disease.

The presence of fever greater than 38. 3 C (101 F) off and on for more than three weeks without a specific cause identified for the fever. Abbreviated FUO. Extensive diagnostic testing can determine the cause in the majority of cases of FUO. FUO may be related to infections such as HIV or other viral infections, cancers, or chronic inflammatory diseases such as sarcoidosis.

Extrapulmonary tuberculosis is the most frequent cause of FUO. Drug-induced hyperthermia, as sole symptom of an adverse reaction to medication, should always be considered.

Disseminated granulomatoses such as Tuberculosis, Histoplasmosis, Coccidioidomycosis, Blastomycosis and Sarcoidosis are associated with FUO. Lymphomas are the most common cause of FUO in adults.

Diagnosis and Treatment

A history and physical exam will be performed. Lab and imaging tests will be done to search for the source of infection or the inflammatory cause of the fever.

Standard Workup : CBC, Chem 12, Lipase, UA, X-Ray, EKG.

Treatment includes: antipyretics (acetaminophen, ibuprofen), treatment of the underlying cause when found including broad spectrum antibiotics if needed. ...