The white blood cell differential determines the ratio of white to red blood cells.

• A. True
• B. False
• C. Determines the ratio of platelets to white cells
• D. Measures only red cell morphology

Answer: (B)

The white blood cell differential tells you the proportions (and sometimes the absolute numbers) of the different white blood cell types—neutrophils, lymphocytes, monocytes, eosinophils, and basophils—among the white cells. It does not tell you the ratio of white to red blood cells. That ratio comes from the complete blood count by comparing the actual counts of white cells to red cells, not from the differential itself. So the statement is false. The differential focuses on characterizing leukocytes, not on counting or comparing red cells or platelets, nor on red cell morphology, which is assessed from smear evaluation and RBC indices rather than the differential.