|Johnson, Luann - UNIV OF NORTH DAKOTA|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2005
Publication Date: May 22, 2005
Citation: Hunt, J.R., Hadley, K.B., Johnson, L.K. 2005. Serum prohepcidin was not associated with iron absorption by healthy women in a dose-response assessment of elemental iron powders [abstract]. First Congress of the International BioIron Soiety. p. 57. Technical Abstract: The relationship between an administered iron dose and the fractional absorption of 59Fe radiolabel was measured in women to assess whether a) the bioavailability of commercial elemental iron powders could be estimated by the displacement of the radiolabel, and b) serum prohepcidin (84 amino acid) peptide was related to iron absorption. Volunteers were 28 healthy females, 21-51 y, with hemoglobin 120-152 g/L, and serum ferritin 4-122 µg/L. Iron absorption was measured biweekly, 8 times. Fasted volunteers were administered water and gelatin capsules containing 0.2 µCi 59Fe with 0.5 mg carrier Fe as FeSO4, and an additional 0, 2.5, 7.5 or 50 mg Fe as FeSO4, 2.5 or 10 mg electrolytic iron, or 2.5 or 10 mg reduced iron. The lowest dose was tested first, and the order subsequently randomized. Radiotracer absorption was determined by whole body counting at day 13. Fasting blood was collected 1 d before and 16 wk after the initial absorption measurement and stored at -80ºC. Serum prohepcidin was measured by competition ELISA (DRG Intl. Inc., Germany). Fe absorption and serum prohepcidin, ferritin, and C-reactive protein (CRP) data were logarithmically transformed. Absorption of the radiotracer fit a dose-response power curve (Ln(% radioiron retention) = 24.2 - 0.155*Ln(mg Fe administered as FeSO4); r = -0.39, p < 0.0001). Displacement of radioiron retention with added elemental iron powders tended to be less than with equivalent doses of FeSO4. However, the variation in the retention data was too great to determine a relative bioavailability for the elemental powders that differed significantly from either 0 or 100% that of FeSO4. Serum prohepcidin ranged from 99 to 376 with a geometric mean of 184 ug/L and CVs of 6.6 and 2.8% for inter- and intra-individual variation, respectively. Prohepcidin correlated with serum ferritin (r= 0.47, p<0.01), but was unrelated to the initial Fe absorption measurement (NS), in contrast to serum ferritin (r= -0.57, p<0.01), mg body Fe/kg (r= -0.53, p<0.01; based on ln(serum transferrin receptor/ferritin), Cook, 2003), or C-reactive protein (r=-0.37, p<0.05). Prohepcidin did not correlate with C-reactive protein, transferrin receptor, transferrin saturation, or hemoglobin. In non-anemic women with a range of normal Fe stores, serum prohepcidin did not predict Fe absorption.