Serum pro-hepcidin concentrations and their responses to oral iron supplementation in healthy subjects manifest considerable inter-individual variation.

Hepcidin participates in the regulation of iron homeostasis and its precursor pro-hepcidin can be measured in serum. We evaluated pro-hepcidin serum concentrations in healthy subjects and the possible effects of iron supplementation on the results. The results suggest extensive physiological variation in serum pro-hepcidin concentrations between healthy subjects with no symptoms or signs of anaemia, infections, inflammations, chronic disease or other interpretative factors. Before pro-hepcidin measurements can be used in clinical practise, further investigations are required to identify the physiological factors affecting normal serum pro-hepcidin variations in healthy subjects. The responses of serum pro-hepcidin to a 100-mg oral dose of iron also showed considerable inter-individual variation. In male subjects, no systematic changes in serum pro-hepcidin concentrations were found and the increase in serum iron was fairly modest. In nine out of the ten female subjects who had rather low amounts of storage iron, iron supplementation was followed by an increase in both serum iron and serum pro-hepcidin concentrations. There were considerable inter-individual differences in the timing and magnitude of the response. We also evaluated the conceivable influences of sample storage and freeze-thaw cycles on the results of serum pro-hepcidin ELISA. We did not observe any changes in the results after serum samples were frozen and thawed up to four times and/or stored at room temperature for up to 6 h.