CHr: early indicator of iron deficiency and response to therapy. Histogram of red blood cells (gray area) and reticulocytes (black area) hemoglobin content (picograms per cell) before and 4 and 13 days after intravenous administration of iron dextran in a patient unresponsive to oral iron therapy. Values at day 0 were hemoglobin 7.8 g/dL, mean corpuscular hemoglobin 16 pg, reticulocytes 1.8%, CHr 16 pg. Values at day 4 were hemoglobin 8.7 g/dL, mean cell hemoglobin 17.3 pg, reticulocytes 6.4%, CHr 26 pg. Values at day 13 were hemoglobin 11.2 g/dL, mean cell hemoglobin 20.8 pg, reticulocytes 3.4%, CHr 27.1 pg.²