Utilization of supplemental iron by premature infants fed fortified human milk

We measured red blood cell iron incorporation (RBC-inc) in 13 human milk-fe d premature infants (birthweight 1037 +/- 289 g, gestational age 27 +/- 2 w k, weight at start of study 1571 +/- 426 g) who were receiving full tube-fe edings of human milk fortified with a commercial human milk fortifier (Fort HM). The relative RBC-inc of supplemental iron (2 mg/kg/d of ferrous sulfat e) was assessed using Fe-57 sulfate mixed directly into a 24-h volume of Fo rtHM, and Fe-54 sulfate given as a bolus between two FortHM feedings the ne xt day. RBC-inc was similar between the two methods of supplemental iron ad ministration (4.7 +/- 2.5% vs 4.6 +/- 1.5%, respectively). Although these v alues are lower than RBC-inc expected from iron native to human milk, the r elatively large amount of iron in the supplements contributed most of the i ron incorporated into RBC by the infants. There was a significant positive correlation between the reticulocyte count and RBC-inc. As the high nutrien t (especially calcium) content of the FortHM did not interfere with iron ut ilization, adding iron directly to FortHM, or incorporating it into commerc ial fortifiers, may be a practical method to provide iron to premature infa nts.