High absolute reticulocyte values may be a sign of hemolytic anemia or a post-treatment reaction. Reticulocytes are precursor cells to red blood cells, and when they are markedly elevated, it is often indicative of active proliferation of the bone marrow erythroid lineage, which is often seen in two clinical situations. One condition is hemolytic anemia, which is a group of anemic disorders caused by increased destruction of red blood cells. Clinically, autoimmune hemolytic anemia and paroxysmal sleep hemoglobinuria are common. When hemolytic episodes occur, reticulocytes are markedly elevated. Another situation is the treatment response, such as iron deficiency anemia iron supplementation therapy, megaloblastic anemia supplementation of folic acid, vitamin B12 therapy, when the treatment is effective, reticulocytes will be significantly elevated. Therefore, a high absolute reticulocyte value is recommended to consult a doctor for further examination to clarify the etiology.