What is the term for an abnormally reduced number of red blood cells in a sample of blood?

The term for an abnormally reduced number of red blood cells in a sample of blood is erythropenia. This condition indicates a deficiency in the number of red blood cells, which can lead to various health issues, including anemia. Understanding this term helps in recognizing and diagnosing conditions related to blood health.

In contrast, polycythemia refers to an increase in red blood cells, thus it does not fit the description. Hemorrhage denotes blood loss, typically through bleeding, which can temporarily reduce red blood cell counts but is not a direct description of the condition itself. Leukocytopenia refers specifically to a reduced number of white blood cells, which is unrelated to red blood cell counts. Recognizing these distinctions clarifies why erythropenia is the correct choice for describing a lower-than-normal level of red blood cells in the bloodstream.