Anisocytosis has to do with red blood cells. Usually, individual red blood cells are roughly about the same size as other red blood cells. Anisocytosis refers to a condition that results in red blood cells being different sizes. This happens usually because of another disease that is present in the body, usually some type of anemia. Symptoms of anisocytosis are shortness of breath, fatigue, and heart pounding. These symptoms are usually present because the body cannot carry oxygen effectively. Some cases are relatively mild while other cases can be fairly severe. This is why it is important to have the condition treated properly.