May8 M2-Fever of Unknown Origin Flashcards
4 types of FUO
- classic FUO
- nosocomial FUO
- neutropenic FUO
- FUO assoc with HIV infection
- all need >38.3 on several occasions and 2+ days of microbiology
nosocomial FUO def
- hospitalized, acute care and no dx of infection when admitted
- 3 days under investigation
neutropenic FUO def
- ANC<500
- 3 days under investigation
- start empiric Abx coverage immediately**
HIV associated FUO Def
- confirmed HIV+
- 3 days under investigation, 4 weeks as outpatient
classic FUO
- all other cases with fever of at least 3 weeks
- 3 days or 3 outpatient visits or 1 week of intelligent and invasive ambulatory investigations
(imp?) only case of FUO where you start empiric Abx
neutropenic FUO
3 broad categories of causes of FUO
- infectious
- neoplastic
- inflammatory/CTD (connective tissue disease)
occult infectious sources causing FUO that are still important
- occult abscesses
- localized (prostatitis, cholangitis, sinusitis, dental abscess)
- IE
- TB
- organisms difficult to culture
- fungal disease
- prolonged viral syndromes (EBV, CMV, HIV)
noninfectious cause of FUO that is starting to become more prevalent
inflammatory and autoimmune causes (all rheumatology basically: granulomatous disease, temporal arteritis, polymyalgia rheumatica, SLE, RA, Wegener’s granulomatosis, polyarteritis nodosa, sarcoid, Crohns, FMF, TRAPS)
especially vasculitis
other causes of FUO than inflam, neoplastic, infectious
- drug fever (antimicrobial, CV, chemo, CNS acting)
- tissue sources
- central peripheral regulatory disorders
- familial disease (FMF, Fabry’s)
- other (habitual hyperthermia, factitious fever = say they have it but they don’t)
things to consider in FUO in elderly and most common thing
- *multisystem disease (temporal arteritis, giant cell arteritis, polymyalgia rheumatica)
- TB and mycobacterial infection
- neoplastic (colon cancer, etc.)
- thrombosis (DVT,etc.)
most common causes of FUO in order
#1 lymphoma #2 collagen VASCULAR disease #3 abscess #4 undiagnosed #5 solid tumor #6 thrombosis or hematoma #7 granulomatous disease #8 endocarditis #9 mycobacterial disease
how does FUO DDx evolve as the time of workup becomes increasingly long
less and less chance of infection or neoplasm
important question to ask in history for patient with FUO
occupation
(imp?) diagnostic test of highest yield, to do first in FUO
CT scan. 19% dx yield. good sensitivity
(imp?) 2 things a CT scan can help identify in FUO
- occult intra-abdominal abscesses
- occult intra-abd neoplasms
(imp?) 2nd most important dx test to do in FUO
PET scan (is the most useful nuclear medicine scan and is more useful than gallium)
(imp?) 2 things that PET scan helps finding especially
- infection
- cancer
- vasculitis (very good at this one)
disease we should always think of when seeing FUO
IE
(imp?) investigation of FUO with the 3rd highest dx yield (but that is done later bc invasive)
liver biopsy. 15% yield.
abnormal liver enzymes or hepatomegaly DON’T indicate for a bx
(imp?) important investigation of FUO in elderly (one of highest dx yields)
temporal artery bx
- 17% dx yield
- often giant cell arteritis
(imp?) other investigations in FUO
- duplex doppler scan (colors) to check for DVT of lower extremities (small % of FUO)
- BM bx (very low dx yield. 1 in 500. do very late)
worst case in FUO: tests performed without evidence
- empiric Abx therapy to check if get petter
- exploratory laparotomy
- markers like ESR, CRP, PCT (procalcitonin), D-dimer (bad)
- bone scan
