Background Hepcidin-25 is a key peptide-hormone of iron metabolism and iron absorption of small intestine. The low hepcidin-25 state leads to an increase in intestinal iron absorption and iron efflux from macrophage. In hemodialysis (HD) patients, iron deficiency is one of the important factors of anemia. However, it remains elusive whether there is a difference in the response to oral iron administration between HD patients with low hepcidin-25 levels and smaller mean corpuscular volume (MCV) and those with normal MCV. Subjects and Methods Hepcidin-25 was measured in 66 patients on maintenance HD. Of the 66 cases, 14 cases with low serum levels of hepcidin-25 (<14ng/ml) were enrolled in the study. We examined the correlation between the based MCV and a gain in hemoglobin (Hb) after oral iron (sodium ferrous citrate) administration. Hb was measured before and 8 weeks after oral iron administration. Serum levels of hepcidin-25 were measured using a high-throughput LC-MS/MS method. Serum levels of ferritin, hepcidin-25, MCV and Hb were measured before starting HD at the beginning of the week when HD became vacant for 2 days. Results In 66 cases, mean serum levels of hepcidin-25 were 14.0+/- 22.6ng/ml. Serum levels of hepcidin-25 were positively correlated with those of ferritin. The MCV was under 88fL in 6 cases (low MCV group, HD duration, 8.7+/-4.4 years, and oral iron dose, 50mg/day), and the other 8 cases showed normal MCV (normal MCV group, HD duration, 7.3+/-4.6 years, and oral iron dose, 62.5mg/day). In low MCV group, Hb significantly increased, but remained unchanged in normal MCV group. A gain in Hb was significantly greater in low MCV group (3.1+/-1.2g/dl, p<0.01) than that in normal MCV group (0.8+/-2.2g/dl). Hb, ferritin and hepcidin-25 levels did not differ between groups. Conclusions In a state of low serum levels of hepcidin-25 and ferritin, oral iron administration is more effective for anemia in patients with low MCV than in those with normal MCV.
