Albertine Donker

Iron Function and Iron Handling from Fetus to Adult 75 2 of growth and development may have unfavorable and long-lasting effects on the function of the involved organs or physiological systems. Both in vitro and in vivo data suggest that iron handling matures during childhood, corroborating our recent study on serum hepcdin values in healthy children (www.hepcidinanalysis.com 42 ). 43 However, how the human body balances between the opposite forces regarding iron metabolism, e.g. the need to acquire large amounts of iron in order to ensure the enormous growth that occurs during childhood versus the need to withhold iron from iron-dependent pathogens that are especially threatening for infants, is still largely unknown. Although both in vitro and in vivo data suggest intact hepcidin signaling in early life, the relative contribution of both stimulating and inhibiting stimuli to hepcidin secretion is unclear. Other in vitro data suggest that the interaction between hepcidin and ferroportin inside the enterocyte changes after weaning from breastfeeding, favoring enhanced iron absorption during the suckling period, which is characterized by a low iron intake. To the best of our knowledge, no in vivo data are available on this topic. Furthermore, understanding how the human body distributes iron between the various iron-demanding compartments during the period from fetus to adult, both in periods of iron homeostasis, iron deficit and iron excess, is limited. Moreover, knowledge on the optimal iron status for the different iron-demanding tissues during human growth and development is largely missing. Finally, the lack of adequate biomarkers of iron status of the various iron-consuming organs in the developing child, and especially the central nervous system, hampers both clinicians and researchers in assessing, possibly treating and exploring (dys)regulation of iron homeostasis.