Bi-daily iron administration at 10:00 am and at 5:00 pm results in increased hepcidin on the consecutive day and decreased iron bioavailability (n = 13). Subjects followed a controlled diet during the day of iron administration (study 3). Boxes indicate median and interquartile ranges, whiskers describe the range of the data (min to max). (A) Hepcidin profiles. (B) Fractional iron absorption at the 3 time points of the 60-mg Fe dose.