White Blood Cell Count (WBC)

White blood cell count is typically measured as part of a Complete Blood Count (CBC), one of the most commonly ordered blood tests in medical practice [2]. The process is straightforward and provides rapid, accurate results using advanced laboratory technology.

**Blood Sample Collection**
The test requires only a small blood sample, usually drawn from a vein in your arm using a standard needle and collection tube. The procedure takes just a few minutes and involves minimal discomfort. No special preparation is typically required, though you should inform your healthcare provider about any medications or supplements you're taking, as some can affect white blood cell counts [2].

**Laboratory Analysis Methods**
Modern laboratories use sophisticated automated hematology analyzers that employ flow cytometry technology to count and categorize blood cells [2]. These machines can process thousands of cells per second, providing highly accurate counts by passing individual cells through laser beams and measuring their size, complexity, and other characteristics.

When automated results appear abnormal or require verification, laboratory technicians may perform manual microscopic counting. This involves examining a blood smear under a microscope, where a trained technologist manually counts cells in specific areas of the slide and calculates the total count [2].

**Factors Affecting Results**
Several factors can influence WBC count accuracy:
• **Time of day**: Counts can vary slightly throughout the day
• **Physical activity**: Recent intense exercise may temporarily elevate counts
• **Stress levels**: Both physical and emotional stress can affect results
• **Medications**: Certain drugs, including corticosteroids and antibiotics, can alter WBC counts
• **Sample handling**: Proper collection and timely processing are crucial for accurate results [2]

**Testing Timeline**
Results are typically available within hours of sample collection, making WBC count an excellent tool for urgent medical situations. In emergency settings, stat (immediate) CBC results can often be obtained within 30-60 minutes, allowing for rapid diagnosis and treatment decisions [2].