Response of various indices of iron status to acute iron depletion produced in menstruating women by low iron intake and phlebotomy

Abstract

We investigated response sensitivities of indices of iron status to controlled iron depletion and repletion in 11 premenopausal women. The women were depleted of storage iron (as reflected by serum ferritin) through a combination of a low-iron diet and phlebotomy. They then consumed a diet containing 13.7 mg of iron per 2000 kcal, supplemented with either ascorbic acid or placebo (for 51/2 weeks) and a daily 50-mg iron supplement (for the subsequent 17 days). The relative sensitivities of different indices for detecting iron depletion were as follows: ferritin > % transferrin saturation > plasma iron > hemoglobin > hematocrit > zinc protoporphyrin (ZnPP) and erythrocyte protoporphyrin (EP). Ascorbic acid treatment during repletion, before iron supplementation, significantly (P <0.05) affected changes in hemoglobin, ZnPP, ZnPP/heme, and EP/heme. Changes in heme synthesis evidently do not occur until iron stores are depleted and, conversely, during iron repletion hematopoiesis must be satisfied before iron stores, as reflected by ferritin, increase. Thus, the use of only one index of iron status is of limited value for detecting iron depletion.