March 31st Wednesday, Fever of Unkown Origin

Hey all,

Nav had talked about FUO on Wednesday. The differential is just as large as that for pancytopenia. The classic definition of 3 weeks outpatient or 1 week inpatient doesn't quite apply the same way as we have great tests, quick PCR and things often become more apparent more quickly.

This is a fantastic article summarizing modern day FUO, http://www.nejm.org/doi/full/10.1056/NEJMp1212725

Some key pearls is to look for VS instability before deciding on starting antibiotics. Infection from osteo, endocarditis, or other type of infections can't be picked up if broad spectrum antibiotics are started. This can be true on the wards as well, if someone spikes a fever and there is no source of infection (or even suspected), doing blood cultures, and monitoring is OK!

Alternatively, if a patient has a fever, and a PICC line that's been present for many days, patient is tachycardic and hypotensive, please try and remove that line (source control) and start empiric antibiotics).

In terms of diagnosis, up to 30% may have no diagnosis but this is variable depending on the study. From pocket medicine infection ~30% TB, intrabdo abscess, Osteo, CMV, EBV, malaria, fungal. 30% connective tissue, Giant cell arteritis, adult onset still's disease Vasculitis.
Neoplasm: lymphoma, renal cell, pancreatic. Miscellaneous: drugs, DVT/PE, hematoma, thryoid, sarcoid, familial mediterranean.

A good history and physical are essential, some important points:

1. while we have a long differential, fever in immunocompromised host (HIV, post transplant, post chemo), fever in a returning traveller, and fever in the ICU are all SEPARATE entities which have their own study and potential etiologies.

Pocket medicine recommends a LOT of investigations, which causes people to order C-ANCA off the bat for FUO... please don't do this.

When nothing is found, the prognosis is GOOD, a good percentage will resolve on their own. There is no need to start empiric antiboitics and one must resist the temptation in a otherwise stable patient, as when the fever resolves you are stuck with the question, is this because of the antibiotics? Or in spite of them?