Fever of unknown origin

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Workup as indicated


  1. CBC/diff, look at WBC morphology: infection, kawasaki, cyclic neutropenia, cancer
  2. Serum electrolyes, LFT's
  3. blood cx, aerobic and anarobic: endocarditis, salmonellosis
  4. Fungal studies as indicated: histoplasmosis, coccidiomycosis, blastomycosis
  5. Stool cx/O&P: salmonella, giardia
  6. Cultures: Obtain cultures for bacteria, mycobacteria, and fungi in all normally sterile tissues and liquids that are sampled during further workup. These tissues and fluids include cerebrospinal fluid (CSF), pleural or peritoneal fluid, and fluid from the liver, bone marrow, and lymph nodes
  7. UA/urine cx: UTI, kawasaki
  8. CRP/ESR: infection, kawasaki, collagen-vascular disease, IBD
  9. PPD
  10. Serologies are most helpful if paired samples show a significant, usually 4-fold, increase of antibodies specific to an infectious microorganism. Brucellosis, CMV, infectious mononucleosis, HIV, amebiasis, toxoplasmosis, and chlamydial diseases are diagnosed by serology.
  11. Hepatitis/viral serologies: CMV, EBV, Hep panel
  12. ANA, Rheumatoid factor, thyroxine level (T4)


  1. CXR/sinus Xray: sinusitis, TB, histoplasmosis
  2. Abdominal US to screen for abscess
  3. Chest/abd CT scan: Tb, liver abscess
  4. Gallium scan/bone scan: osteo
  5. MRI for osteo
  6. GI radioimaging or endoscopy for IBD, etc
  7. Echo for endocarditis

Indications for transfer

Emedicine.com, last update March 8, 2005
The 5 minute pediatric consult, 3rd ed.