Hypotransferrinemia of chronically hemodialyzed patients

Increasingly, the iron needs of hemodialysis patients receiving erythropoietin are being met by infusions of intravenous iron guided by laboratory tests to measure body iron availability. The interpretation of assays based on ferritin and transferrin must take into account the effect of inflammation on both proteins and malnutrition on the latter. In our chronic hemodialysis population, hypotransferrinemia was present in greater than 90% of the patients. Using statistical methods and laboratory studies, we sought to identify the principal reasons for the high prevalence of hypotransferrinemia. We observed that transferrin levels were disproportionately low relative to albumin and prealbumin and correlated inversely with ferritin levels. There was no correlation between transferrin and the soluble transferrin receptor. After the infusion of 900 mg of iron, transferrin saturation increased and total transferrin decreased so that unsaturated iron bonding capacity decreased as well. Ferritin concentrations increased significantly after iron loading. Attempts to demonstrate activation of the patients' antioxidant mechanisms associated with iron infusion were negative. We concluded that the low transferrin may be principally the result of diminished synthesis related to the chronic inflammatory status of hemodialysis patients, which favors production of ferritin, but iron and nutritional status may also influence the blood transferrin concentration. These factors make interpretation of transferrin-dependent assessment of body iron stores unreliable and can result in inadequate or overly aggressive iron-replacement therapy.