The circulating non‐transferrin‐bond iron (NTBI) response to 100 mg of ferrous sulfate iron is unrelated to iron status or gender

Background Women may arguably be less susceptible to conditions related to oxidative stress than men. Mediation of some forms of systemic oxidation has been attributed to circulating NTBI. Objective To compare the circulating NTBI response after 100 mg of iron from FeSO4 in adults with contrasting (high vs low) Fe status. Methods Plasma samples were obtained in 10 subjects of each sex at 0, 90, 180, and 270 min after ingestion of 100 mg of FeSO4 iron in 200 mL of water in the fasting state, and analyzed for [Fe] with a ferrozine‐based assay and [NTBI] by a dialysis‐binding fluorometric detection method. Results Plasma [ferritin] ranged from 50 to1640 μg/L in men and from 6 to 28 μg/L in women. Whereas median the ∑ 270‐min Fe response was 3.5 X higher (671 vs 210 μg/dL, p<0.001) in the female group, the respective cumulative effects for ∑ NTBI were indistinguishable:18.4 vs 21.2 μg/dL, p=0.81. Slopes of the regression equation of y=[NTBI] to x=[Fe] were 0.022 in females and 0.077 in males. Conclusion Circulatory exposure to NTBI after FeSO4 was equivalent across comparison groups, probably due to adaptations related to iron‐status differences, but an independent gender effect cannot be excluded. Funded by the Hildegard Grunow Foundation