Final answer:
An increase in white blood cell count above normal levels is called leukocytosis, which is different from leukopenia where there's a condition of too few white blood cells. Unlike erythrocytosis which is an increased red blood cell count, leukocytosis indicates a proliferation of white blood cells that might be nonfunctional, elevating disease risk.
Step-by-step explanation:
An increase in white blood cell count above normal levels is called leukocytosis. This condition indicates excessive leukocyte proliferation. Although a person with leukocytosis has high white blood cell counts, these cells can often be nonfunctional, placing the individual at an increased risk for disease. In contrast, leukopenia is a condition characterized by a below-normal production of leukocytes, which can make an individual unable to ward off diseases effectively.
It's important to distinguish these conditions from other hematologic conditions such as erythrocytosis which refers to an elevated red blood cell count, and erythropoiesis, which is the process of red blood cell formation. Other terms related to blood cell production include polycythemia, an elevated level of hemoglobin found in various conditions, and positive chemotaxis, the process in which cells move toward higher concentrations of a chemical stimulant, commonly seen during an immune response.