(P11-037-23) Stool Hepcidin Concentrations Reflect Stool Iron Levels in Children Following Consumption of Supplemental Iron: A Randomized, Double-Blind, Cross-Over Trial

Objectives: The WHO recommends daily iron supplementation for infants and children (6 mo – 12 y). The recommended dose of iron is set high to deliver adequate absorbed iron due to low rates of dietary iron absorption. Thus, most of the iron accumulates in the colon and is excreted in stool. Iron accumulation in the colon has been associated with gastrointestinal discomfort and increased incidence of enteric infection. The objective of this study was to determine transit time and stool iron concentrations following consumption of supplemental iron. A secondary objective was to determine whether hepcidin could be detected in stool, and if stool hepcidin concentrations reflect changes in stool iron concentrations.

Methods: Children aged 5-12 y (n=10) were enrolled in this randomized, double-blind, crossover trial. Participants provided a baseline stool sample before consuming a standardized breakfast meal containing 54 mg of elemental iron from 2 sources (authors remain blinded) and blue dye to measure transit time. Stool samples were collected until blue dye was no longer detected. Following a 1 wk washout, participants crossed over to the other arm. Stool iron was measured by flame AAS. Stool hepcidin was measured by ELISA. Data were analyzed by 2-way ANOVA with main effects of time, iron source, and their interaction.

Results: Blue dye was first detected in stool 23 ± 8 h (range: 4 – 73 h) after ingestion of iron and was detected for 104 ± 6 h (range: 71 – 204 h). Stool iron did not differ between iron sources (P = 0.84). Baseline stool iron was 187 ± 51 and peaked at 733 ± 140 µg iron/g stool (P < 0.0001) following consumption of supplemental iron. Stool hepcidin increased from 356 ± 6 at baseline to 425 ± 19 ng hepcidin/g stool (P = 0.01) following consumption of supplemental iron and when iron in stool was at its peak. When examining individual participant responses over time, changes in stool hepcidin concentrations visually reflected changes in stool iron concentrations.

Conclusions: Stool iron concentrations increase following ingestion of supplemental iron. Our study highlights the variability of gut transit time in children, underscoring the need to better understand the effects of prolonged iron accumulation in the colon. To our knowledge, this is the first study to report hepcidin in stool and warrants further study.

Funding Sources: Intramural funds to SRH