Iron homeostasis in mammals is maintained at the level of iron absorption by the gut. Hepcidin plays a central role in homeostasis by binding to ferroportin and regulating cellular iron export. We found that mice weaned onto diets ranging from 35–350 mg Fe/kg for a period of 4 wk did not change body iron levels as measured by organ iron content and hematological parameters. Direct measure of absorption of 59Fe administered by gavage revealed an inverse correlation between dietary iron content and absorption. Gavage experiments were done following a 4h fast when the stomach and proximal small bowel were free of dietary content. Although iron absorption changed, liver expression of hepcidin mRNA did not. We measured the absorptive response in mice weaned onto diets containing 35 mg Fe/kg for 4 wk and abruptly changed to 350 mg Fe/kg. There was no change in iron absorption at day 1 but by day 3 absorption was reduced nearly 3-fold compared to controls and remained at this level for at least 7d. During this time neither liver nor spleen iron content changed but transferrin saturation increased approximately 1.5-fold. Most importantly, serum hepcidin levels, measured by a competitive binding assay (
Disclosures: No relevant conflicts of interest to declare.