Which condition is characterized by increased white blood cell counts?

The condition characterized by increased white blood cell counts is leukocytosis. This term specifically refers to a higher than normal number of white blood cells (WBCs) in the bloodstream, which can be a reaction to various factors including infections, inflammation, stress, or more serious conditions such as leukemia. The body's response to fight off infections often results in an increase in WBC production, leading to leukocytosis.

In contrast, leukopenia indicates a decreased white blood cell count, which can make a person more susceptible to infections. Anemia relates to a deficiency of red blood cells or hemoglobin, impacting oxygen transport in the body. Thrombocytopenia refers to a low platelet count, affecting blood clotting abilities. Thus, while the other conditions involve changes in blood cell counts, only leukocytosis specifically denotes an increase in white blood cells.