Which lab value defines leukopenia?

Which lab value defines leukopenia?

• A. WBCs < 4x10^9
• B. WBCs < 5x10^9
• C. WBCs < 3x10^9
• D. WBCs < 6x10^9

Answer: (A)

Leukopenia means having too few white blood cells, which are key for fighting infections. The commonly used cut-off for defining leukopenia is a white blood cell count below 4 x 10^9 cells per liter, since that is the lower limit of the normal range (roughly 4–11 x 10^9/L). Therefore, the lab value that defines leukopenia is a WBC count less than 4 x 10^9/L. Counts around 3 x 10^9/L are leukopenic, while values near 5 or 6 x 10^9/L are typically within normal limits. This threshold helps clinicians identify patients at higher risk of infection and consider possible causes or treatments, especially in HIV or patients receiving therapies that can suppress bone marrow.

Leukopenia means having too few white blood cells, which are key for fighting infections. The commonly used cut-off for defining leukopenia is a white blood cell count below 4 x 10^9 cells per liter, since that is the lower limit of the normal range (roughly 4–11 x 10^9/L). Therefore, the lab value that defines leukopenia is a WBC count less than 4 x 10^9/L. Counts around 3 x 10^9/L are leukopenic, while values near 5 or 6 x 10^9/L are typically within normal limits. This threshold helps clinicians identify patients at higher risk of infection and consider possible causes or treatments, especially in HIV or patients receiving therapies that can suppress bone marrow.