Earliest response to iron supplementation in iron deficiency anemia is denoted by?

Response to iron therapy: Rapid subjective improvement, with disappearance or marked reduction of fatigue, lassitude, and other nonspecific symptoms, before any improvement in anemia is observed. Earliest hematologic evidence of response to treatment is an increase in reticulocytes on 5th to 10th day after sta of supplementation therapy & thereafter returns to normal. There is steady improvement in Hb and normalization of red cell indices. RETICULOCYTE IN BLUE LINE