Management of Leukocytosis and Neutrophilia Without Fever

Diagnostic Evaluation

A WBC count of 14,300 cells/mm³ with absolute neutrophil count of 11,097 cells/mm³ warrants a careful assessment for bacterial infection even without fever, as this degree of leukocytosis has a likelihood ratio of 3.7 for underlying bacterial infection 1, 2
Obtain a manual differential count immediately to assess band forms and other immature neutrophils, as automated analyzers are insufficient for this critical determination 1, 3
An absolute band count ≥1,500 cells/mm³ has the highest likelihood ratio (14.5) for detecting documented bacterial infection 1, 2
A left shift (percentage of band neutrophils ≥16%) has a likelihood ratio of 4.7 for bacterial infection, even with a normal total WBC count 1, 2, 3

The absence of fever does not exclude bacterial infection, particularly in older adults where typical symptoms are frequently absent 1, 4
Obtain chest radiograph to evaluate for pneumonia, as leukocytosis has been associated with increased mortality in nursing home-acquired pneumonia 1, 3
Consider pulse oximetry if any respiratory symptoms are present 3
Do NOT perform urinalysis or urine culture if the patient is completely asymptomatic, as asymptomatic bacteriuria should not be treated 1, 2
If urinary symptoms are present, perform urinalysis for leukocyte esterase and microscopic examination for WBCs 1, 2
Only obtain urine culture if pyuria is present (≥10 WBCs/high-power field or positive leukocyte esterase) 2

Initiate targeted antimicrobial therapy based on the identified source and local resistance patterns 5
Limit antibiotic duration to 4-7 days if source control is adequate 5
Consider empiric antimicrobial therapy if the patient has other signs of infection or if band count is elevated, given the high likelihood ratio for bacterial infection 1, 2, 5
Serial WBC counts are essential to track response to therapy 5
Do NOT initiate antibiotics based solely on the elevated WBC count if the patient is completely asymptomatic with no clinical signs of infection 5
Monitor closely with repeat CBC in 12-24 hours and reassess for development of symptoms 1

Do not dismiss the significance of leukocytosis simply because fever is absent—older adults frequently present with atypical infection manifestations 1, 4
Do not treat asymptomatic bacteriuria discovered during workup, as this does not improve outcomes and promotes resistance 1, 2
Do not rely on automated differential counts alone—manual differential is necessary to accurately assess band forms 1, 3