A complete blood count (CBC) is not a single marker but a panel that evaluates red blood cells, white blood cells, and platelets. It includes measures such as hemoglobin, hematocrit, MCV, RDW, WBC count and differential, platelet count, and sometimes additional indices like NRBCs or immature granulocytes.

Because it samples multiple blood cell lines at once, the CBC provides a broad overview of hematologic and inflammatory health. It can screen for anemia, infection, immune activation, bleeding risk, and marrow disorders. In healthy individuals, it is one of the most information-dense routine labs, but most meaningful interpretation comes from patterns across the panel rather than any single number in isolation.