Using the given data, what is the lymphocyte count per microliter?

Using the given data, what is the lymphocyte count per microliter?

• A. 1,100
• B. 5,500
• C. 2,200
• D. 550

Answer: (A)

The key idea is to turn the percentage of lymphocytes into an absolute count by multiplying the total white blood cell (WBC) count by the lymphocyte fraction. Lymphocytes per microliter = (WBC per μL) × (percent lymphocytes as a decimal). For example, if the WBC count is 5,500/μL and lymphocytes make up 20% of the differential, the lymphocyte count is 5,500 × 0.20 = 1,100/μL. This matches the given answer. In practice, you take the WBC value and the lymphocyte percentage from the differential, convert the percentage to a decimal, multiply, and report per microliter.

The key idea is to turn the percentage of lymphocytes into an absolute count by multiplying the total white blood cell (WBC) count by the lymphocyte fraction. Lymphocytes per microliter = (WBC per μL) × (percent lymphocytes as a decimal).

For example, if the WBC count is 5,500/μL and lymphocytes make up 20% of the differential, the lymphocyte count is 5,500 × 0.20 = 1,100/μL. This matches the given answer. In practice, you take the WBC value and the lymphocyte percentage from the differential, convert the percentage to a decimal, multiply, and report per microliter.