WBC Count
Overview
WBC count measures total circulating leukocytes per microliter of blood, reflecting systemic immune response and bone marrow production. White blood cells include neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each mediating specific immune functions against infection, inflammation, or allergy. Elevated counts (leukocytosis) indicate infection, inflammation, leukemia, or steroid use, while low counts (leukopenia) suggest bone marrow suppression, viral infection, or chemotherapy; clinically useful as first-line screening for infection, monitoring chemotherapy toxicity, and initial leukemia evaluation.Clinical Use Cases
- Diagnosing bacterial infections (neutrophilia).
- Monitoring chemotherapy-induced neutropenia.
- Screening for leukemia and lymphoma.
- Assessing inflammatory conditions (rheumatoid arthritis, IBD).
- Evaluating immune status in HIV/AIDS.
Specimen Types
- Whole blood (EDTA tube).
- Capillary blood (point-of-care).
Measurement Methods
- Automated hematology analyzer (impedance/flow cytometry).
- Manual chamber counting (hemocytometer).
- Point-of-care analyzers.
Test Preparation and Influencing Factors
- No fasting required.
- Recent exercise, stress, or convulsions elevate count.
- Corticosteroids cause demargination leukocytosis.
- Chemotherapy, viral infections suppress marrow.
- Time of day variation (higher morning).
Synonyms
- Leukocyte count.
- White cell count.
- Total WBC.