In patients with iron deficiency anemia, effective iron dosing is manifested by an increase in hemoglobin and an increase in reticulocytes. The earliest manifestation is an increase in reticulocytes, and as reticulocytes rise, so does hemoglobin. As the hemoglobin rises, the reticulocytes gradually decline to normal, and the hemoglobin rises progressively to normal. Patients with iron deficiency anemia who are taking iron supplements should continue to take iron supplements if the routine blood tests and reticulocyte tests indicate that the iron supplements are effective. If hemoglobin and reticulocytes are monitored during iron supplementation and the assessment of iron supplementation is not effective, further investigation is needed to find out what is the reason for the ineffectiveness of iron supplementation.