Medical Term for Elevated White Blood Cell Count
The medical term for an elevated white blood cell (WBC) count is "leukocytosis." 1
Definition and Thresholds
Leukocytosis is specifically defined as a leukocyte count ≥14,000 cells/mm³ according to the Infectious Diseases Society of America guidelines. 1 This threshold has a likelihood ratio of 3.7 for detecting bacterial infection. 1, 2
Clinical Context and Terminology
The term "leukocytosis" is used universally across medical specialties to describe this laboratory finding. 3, 4, 5 When the WBC count exceeds 100,000 cells/mm³, the specific term "hyperleukocytosis" is used, which represents a medical emergency due to risk of cerebral infarction and hemorrhage. 6, 4, 7
Related Important Terms
Left Shift
When leukocytosis is accompanied by increased immature neutrophil forms (band neutrophils ≥16% or absolute band count ≥1,500 cells/mm³), this is termed a "left shift," which has even higher diagnostic accuracy for bacterial infection than leukocytosis alone. 1, 8
Specific Cell Type Elevations
- Neutrophilia: Elevated neutrophil count specifically 4, 5
- Lymphocytosis: Elevated lymphocyte count 5
- Eosinophilia: Elevated eosinophil count 4, 5
Clinical Significance
The presence of leukocytosis warrants careful assessment for underlying causes, most commonly bacterial infection, but also including physical/emotional stress, medications (corticosteroids, lithium, beta-agonists), chronic inflammatory conditions, and less commonly, primary bone marrow malignancies. 3, 4, 5