[Iron supplementation is recommended in renal anemia]

The main causes for renal anemia are insufficient erythropoietin production and absolute and/or functional iron deficiency. Absolute iron deficiency occurs with blood losses (most common are gastro-intestinal bleedings and hemodialysis treatments) or inadequate iron absorption in the gut (mainly due to increased circulating hepcidin or treatment with erythropoiesis stimulating agents). The explanation for functional iron deficiency is the high level of circulating hepcidin found in chronic kidney disease patients. The transmembrane iron transporter ferroportin is internalized and degraded by hepcidin with subsequent decreased iron absorption from the gut and reduced mobilization from iron storing cells. Thus, the bioavailability of iron is decreased despite normal or high total iron content. The diagnosis of iron deficiency in chronic kidney disease can be problematic because inflammation is common, leading to false high circulating ferritin and false low transferrin saturation. Treatment with iron is recommended in chronic kidney disease patients to prevent or minimize anemia symptoms or to reduce the need for treatment with erythropoiesis stimulating agents or blood transfusions. Intravenous iron is recommended in patients on dialysis treatment but in non-dialysis patients, a 1-3 month trial of oral iron can be tried. However, this is seldom sufficient in patients treated with erythropoiesis stimulating agents.