| Fever of Unknown Etiology | ||
Susan E. Coffin
| Database Differential Diagnosis Approach to the Patient Data Gathering Physical Examination Laboratory Aids Common Questions and Answers Bibliography |
| DATABASE | ||
DEFINITION
Fever of unknown origin (FUO) is defined as a febrile illness (38.5°C on multiple occasions) that has been present for more than 10 days, with no apparent source despite careful history taking, physical examination, and preliminary laboratory studies.
| DIFFERENTIAL DIAGNOSIS | ||
CAUSES
FUO is more often an unusual presentation of a common disease than a common presentation of an unusual disease. An underlying cause is never established in approximately 10% to 20% of cases. Possible etiologies include:
Uncommon causes of FUO include:
| APPROACH TO THE PATIENT | ||
GENERAL GOALS
Find the cause of the fever and begin treatment of the underlying illness.
phase 1: Attempt to diagnose more common causes of fever. Also observe the pattern of fever.
phase 2: Begin invasive studies to seek rarer forms of fever such as lymphoma, burcellosis, babeosis, subacute bacterial endocarditis (SBE).
phase 3: Reexamine patient and repeat tests to reconsider etiologies such as JRA, sarcoidosis, factitious fever.
| DATA GATHERING | ||
HISTORY
Question: Exposure to animals?
Significance: Cat-scratch
disease, brucellosis, tularemia, leptospirosis
Question: Travel history?
Significance: Malaria, fungal
infection, coccidiomycosis, blastomycosis
Question: Ingestion of raw meat, fish, unpasteurized milk, or
contaminated water?
Significance: Trichinosis, TB, hepatitis,
giardiasis
Question: Pica?
Significance: Fungal infection
Question: Change in behavior or activity?
Significance:
Brain tumor, TB, EBV, Rocky Mountain spotted fever
Question: Pattern of fever?
Significance: May correlate with
underlying etiology, but unlikely.
Question: Height of fever?
Significance: Heat intolerance,
typhoid
Question: Medications (including over-the-counter medications and eye
drops)?
Significance: Drug fever, atropine-induced fever
Question: Well water ingestion?
Significance: Giardia
infection
Question: Evidence of behavior problems?
Significance:
Factitious fever
| PHYSICAL EXAMINATION | ||
Finding: Impaired weight gain or linear growth
Significance:
Collagen disease, malignancy, IBD
Finding: Toxic appearance
Significance: Kawasaki
syndrome
Finding: Rash, sparse hair
Significance: Systemic lupus
erythematosus
Finding: Conjunctivitis
Significance: Kawasaki syndrome
Finding: Fundoscopic lesions
Significance: Brain tumor, TB,
systemic lupus erythematosus
Finding: Sinus tenderness
Significance: Sinusitis
Finding: Nasal discharge
Significance: Sinusitis
Finding: Pharyngitis
Significance: Kawasaki syndrome,
EBV
Finding: Tachypnea
Significance: SBE
Finding: Rales
Significance: Histoplasmosis, sarcoidosis,
coccidiomycosis
Finding: Cardiac murmur
Significance: SBE
Finding: Hepatosplenomegaly
Significance: Hepatitis, EBV
Finding: Rectal abnormalities
Significance: Pelvic abscess,
IBD
Finding: Arthritis
Significance: JRA, IBD
Finding: Bony tenderness
Significance: JRA, leukemia,
osteomyelitis
| LABORATORY AIDS | ||
The laboratory evaluation for a child with FUO should be directed toward the most likely diagnostic possibilities. All patients should have:
Test: CBC with differential and careful examination of WBC
morphology
Significance: Kawasaki, cyclic neutropenia
Test: Blood cultures
Significance: Endocarditis,
salmonellosis
Test: Urinalysis and urine culture
Significance: UTI,
Kawasaki
Test: ESR and/or C-reactive protein
Significance: Collagen
disease
Test: PPD skin test
Significance: TBAdditional studies to be
considered include:
Test: Chest and/or sinus x-ray studies
Significance: TB,
sinusitis, histoplasmosis
Test: Stool bacterial culture and examination for ova and
parasites
Significance: Salmonella
Test: Bone marrow examination and culture
Significance:
Salmonella, histoplasmosis
Test: Slit lamp examination
Significance: Kawasaki
Test: Chest and/or abdominal CT scan
Significance: TB, liver
abscess
Test: Gallium scan
Significance: Osteomyelitis
| COMMON QUESTIONS AND ANSWERS | ||
Q: How do you explain factitious fever?
A: The patient may
twirl the thermometer under their tongue. If left unattended, the child may
place the thermometer under hot water or shake it to elevate temperature
reading.
Q: When should antibiotics be used?
A: Empiric use of
antibiotics should be avoided because of the risk of delaying the discovery of
the appropriate underlying diagnosis. A trial of antipyretics may be considered
if collagen vascular disease is likely.
| BIBLIOGRAPHY | ||
Hoberman A, Wald ER. Urinary tract infections in young febrile children. Pediatr Infect Dis J 1997;16(1):11–17.
Lorin MI, Feigin RD. Fever without localizing signs and fever of unknown origin. In: Feigin RD, Cherry JD, eds. Textbook of pediatric infectious diseases, 3rd ed. Philadelphia: WB Saunders 1992:1012–1022.
McCarthy PL. The pediatric clinical evaluation and pneumonia. Curr Opin Pediatr 1996;8(5):427–429.
McCarthy PL, Klig JE, Shapiro ED, Baron MA. Fever without apparent source on clinical examination, lower respiratory infections in children, other infectious diseases, and acute gastroenteritis and diarrhea of infancy and early childhood. Curr Opin Pediatr 1996;8(1):75–93.
McClung HJ. Prolonged fever of unknown origin in children. Am J Dis Child 1972;124:544–550.
Miller LC, Sisson BA, Tucker LB, Schaller JG. Prolonged fevers of unknown origin in children: patterns of presentation and outcome. J Pediatr 1996;129(3):419–423.
Pizzo PA, Lovejoy FH, Smith DH. Prolonged fever in children: review of 100 cases. Pediatrics 1975;55:468–473.
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© 2000 Lippincott Williams & Wilkins
M. William
Schwartz, Louis M. Bell, Jr., Peter M. Bingham, Esther K. Chung, David F.
Friedman and Andrew E. Mulberg, The 5 Minute Pediatric Consult