Iron supplementation in nephrology and oncology: what do we have in common?

Anemia is frequently seen in patients with chronic kidney disease and also in those with cancer. There are factors in the pathogenesis of anemia that are common to both clinical conditions, with iron insufficiency, inflammation, and upregulation of hepcidin activity playing a part in both chronic disease states. Diagnostic laboratory markers for detecting functional iron deficiency in renal disease and oncology are not ideal, and the most widely available tests, such as serum ferritin and transferrin saturation, have poor sensitivity and specificity. Other tests incorporating a surrogate for iron sufficiency in the RBC and reticulocyte (such as percentage hypochromic RBCs or reticulocyte hemoglobin content) have greater sensitivity/specificity, but unfortunately these tests are not widely available in many hospital laboratories. Iron supplementation may be given via the oral route, i.m., or i.v., but it is now clear that, in both the nephrology and oncology settings, i.v. iron is superior to oral iron in terms of efficacy. Oral iron is associated with a high incidence of gastrointestinal side effects, and although large epidemiological studies of i.v. iron are reassuring, the long-term safety of parenteral iron is not established in well-designed adequately powered randomized controlled trials.