What condition is characterized by a decrease in the number of red blood cells, white blood cells, and platelets?

Pancytopenia is the condition characterized by a simultaneous decrease in the number of red blood cells, white blood cells, and platelets in the bloodstream. This triad of cytopenias reflects a broader underlying issue with bone marrow function or peripheral destruction of these cells. Causes of pancytopenia can include bone marrow disorders such as aplastic anemia, infiltration of the bone marrow by malignancies, or hypersplenism where the spleen sequesters blood cells.

Other options reflect conditions that involve specific blood cell lineages. Thrombocytopenia refers exclusively to a decrease in platelets, leukopenia pertains to a reduction in white blood cells, and leukocytosis indicates an elevation of white blood cells. Hence, while these other conditions highlight specific deficiencies within the hematologic system, pancytopenia encompasses a more comprehensive deficiency affecting all three major cell types.