We can thus assume that iron absorption amounts to 1 mg/day and iron release from macrophages to 20 mg/day when the serum ferritin level is 100 ng/ml selleck products and maximal iron recycling in macrophages is 25 mg/day. Consequently, as shown in Fig. 3, the estimated relative amount of iron available for erythropoiesis decreases as serum ferritin increases. The concentration
of hepcidin, which can be estimated from the ferritin–hepcidin relationship, is somewhat lower than the half maximal inhibitory concentration of hepcidin observed in cell culture models but may be effective after long-term exposure as is the case under clinical conditions [45, 60]. Fig. 3 Estimated serum hepcidin levels, intestinal iron absorption, iron release from macrophages, and total available iron available for erythropoiesis. These parameters vary according to serum ferritin levels. Based on the relationship between serum ferritin and hepcidin levels, percent nonheme SB202190 order iron absorption, and percent early iron release from macrophages (see Fig. 2), we can estimate the total iron available for erythropoiesis. For these calculations, we assume that iron absorption is 1 mg/day and iron release by macrophages 20 mg/day for a serum ferritin level of 100 ng/ml, and a maximal amount of iron recycling by macrophages of 25 mg/day. Based on these calculations, the estimated amount of iron available for erythropoiesis decreases with increasing concentrations
of serum ferritin Iron usage in Japan and worldwide In the prospective study of the hemodialysis patient cohort of the Japan Dialysis Outcomes and Practice Patterns Study (DOPPS) in 2007, mean Hb and serum ferritin levels were 10.38 g/dl and 224 ng/ml, respectively,
and the percentage of patients with ferritin levels <100 ng/ml was 41.3 % [61]. Of note, the 47.2 % of patients with Hb ≥11 g/dl had ferritin levels <100 ng/ml, and only 40.6 % of them received IV iron. These observations suggested that a substantial percentage of patients could maintain Hb levels >11.0 g/dl without iron supplementation, owing to intestinal iron absorption. Therefore, L-gulonolactone oxidase the amount of iron absorbed from the intestine could compensate for that lost in the blood of these patients. From the 2010 DOPPS Annual Report (http://www.dopps.org/annualreport/index.htm), mean serum ferritin levels were >400 ng/ml in patients from all countries except Japan. In the United States, which represented the majority of patients included in the DOPPS, mean serum ferritin levels were >550 ng/ml, and 73.7 % of these patients were receiving IV iron. As the serum ferritin level is associated with hepcidin, in patients with serum ferritin levels >500 ng/ml iron absorption and iron recycling in macrophages could be minimal. In these situations, less intestinal iron absorption compelled physicians to use IV iron to maintain iron balance, which in turn led to a further increase in storage iron.