Response of serum transferrin receptor to iron supplementation in iron-depleted, nonanemic women.

Serum transferrin receptor (sTfR) concentration has been recognized recently as a reliable indicator of functional iron deficiency, but its response to iron supplementation has not been investigated in marginally iron-deficient women. In this randomized, double-blinded trial, 37 female subjects aged 19-35 y with iron depletion without anemia (hemoglobin > 120 g/L and serum ferritin < 16 microg/L) received an iron supplement or placebo for 8 wk. Iron status was measured before treatment, after 4 wk of treatment, and posttreatment (ie, after 8 wk of treatment). Iron supplementation of these iron-depleted, nonanemic women resulted in a progressive and significant decrease in sTfR and a significant increase in serum ferritin, and prevented a fall in hemoglobin. The responsiveness of sTfR to iron treatment indicated that sTfR is a sensitive indicator of marginal iron deficiency in iron-depleted, nonanemic women, even when their body iron stores were being replenished.