Time course of hemoglobin and serum hepcidin concentrations after saline or BA injection in WT and Erfe-deficient mice.Erfe^−/− mice had lower hemoglobin concentration than WT mice at 21 and 28 days after injection of BA (A). Repetitive phlebotomies caused a slight decrease in hemoglobin by 28 days in both WT and Erfe^−/− mice treated with saline (B). Serum hepcidin concentration was higher on days 14 and 21 after BA injection in Erfe^−/− mice compared with WT mice (C) but was unchanged in saline-injected mice (D). Data shown are means ± SEM and were compared for each time point between WT and Erfe^−/− mice (n = 6 per time point) by 2-tailed Student t test (**P < .01, *P < .05).