Final answer:
The term for variation in red blood cell size is called anisocytosis. It is an important consideration in diagnosing various forms of anemia and in understanding RBC morphology.
Step-by-step explanation:
Variation in red blood cell (RBC) size is called anisocytosis. When examining RBCs, especially in the context of diagnosing anemias, the mean corpuscle volume (MCV) is a common test used to measure the size of these cells.
Normal-sized cells are known as normocytic, smaller cells are known as microcytic, and larger than normal cells are known as macrocytic.
A condition such as sickle cell anemia can also cause a change in the shape of erythrocytes, leading to serious complications due to abnormally shaped cells obstructing blood flow.